Solve a mystery, save a life.
"Our patients don't need doctors. Our patients need detectives."
— Dr. John Watson
Watson is an American television series for CBS, starring Morris Chestnut as Dr. John Watson, the secondary protagonist from Sir Arthur Conan Doyle's Sherlock Holmes stories. It is a Spiritual Successor to CBS' previous Holmes adaptation Elementary, which although set in a different continuity (that series starred Lucy Liu as Watson), shared some of the same creative team, including Watson's showrunner Craig Sweeny. The series premiered on January 26, 2025.
Six months on from Sherlock's apparent demise at the hands of his arch nemesis James Moriarty, Watson has set up shop as the head of the Holmes Clinic for Diagnostic Medicine: a medical centre in Pittsburgh dealing with unusual ailments. Watson applies Holmes's deductive methods to his cases, adapting them to suit his medical skills. Unbeknownst to him, Moriarty has survived and has set his sights on the good doctor...
The main cast also features Eve Harlow, Peter Mark Kendall, Inga Schlingmann, Ritchie Coster and Rochelle Aytes. Recurring actors includes Robert Carlyle as Holmes.
In March 2025, the show was renewed for a second season, which premiered on October 13. After two seasons, CBS cancelled the show. The final episode aired on May 3, 2026.
Previews: Teaser Trailer
, First Trailer, Second Trailer
Watson contains examples of:
- Abusive Parents: Ingrid and Gigi's father was physically abusive to them, pinching them both on the arms hard enough to leave bruises whenever they did something he didn't like. He inadvertently caused Gigi's fall, which left her paraplegic, through this abuse, driving Ingrid to kill him to ensure he couldn't do anything worse to her sister.
- Adaptational Intelligence:
- The Watson of the books was by no means stupid but he was, well, The Watson, an Audience Surrogate whose role was to never, ever make the deduction and solve the case, so Sherlock Holmes would look brilliant when he did. Conversely, Chestnut's incarnation is a brilliant detective almost as clever as Holmes himself. Justified since Watson is a medical doctor and Holmes's stories are usually about Holmes solving crimes, it would make sense that Watson's intelligence would shine through more in stories about solving medical mysteries. When Watson seeks Holmes's help in a case where murders are being committed in a medical facility, he reverts to his usual characterization of being astounded by Holmes.
- Inspector Lestrade is usually portrayed as a very average detective Overshadowed by Awesome. In this series, Detective Lestrade is able to deduce Shinwell's Dark and Troubled Past with a single look.
- Adaptational Job Change:
- In her debut appearance, Mary Morstan was a governess. In this series, she shares her husband's career in medicine.
- According to the brief mention we get of Mrs. Hudson, she is now an escort whose services Sherlock frequented. She pretended to be a housekeeper to avoid prying from Watson, but the doctor wasn't fooled. It's also implied that "Mrs. Hudson" isn't her real name.
- Irene Adler has gone from being an opera singer to a seasoned con-artist (a frequent case in adaptations).
- Adaptational Location Change: The show is set in Pittsburgh (with most of the filming taking place in Vancouver).
- Adaptational Nationality: For John Watson, Mary Morstan and James Moriarty. In the original stories, they were British. Their actors maintain their natural American accents. Likewise, Lestrade is now a veteran of the Pittsburgh PD, as opposed to Scotland Yard.
- Adaptation Relationship Overhaul: In the books, John and Mary Watson remain happily married until the latter's death. In the show, it's established from the start that they are in the process of getting divorced, with Mary having resumed using her maiden name of Morstan.
- Adventures in Comaland: Most of the episode "Unsolved Mysteries" is an extended hallucination Watson experiences while unconscious after a car accident.
- Age-Gap Romance: In Season 2 Shinwell gets into a romance with Nurse Carlin DaCosta, with her eventually proposing marriage, which he accepts. There is a 21 year age gap between his actor and hers.
- All for Nothing: In "A Third Act Surprise", Doctor Oliver Day commits suicide so that his previously-unknown daughter (from an illegal sperm donation) can receive one of his kidneys while he doesn't have to face the damage to his reputation, but it turns out that he had been drinking so much before his death that his kidneys are damaged and useless for donation.
- All There in the Manual: In "Take a Family History", the nurse who recommends Mary to the teenage Ingrid is supposedly a younger Watson. This isn't revealed onscreen, and at no point does is this addressed by the characters in the present day. The only way audiences would realise it was Watson, and not just some random nurse, is if they looked at promotional material, as actor Kevin Vidal's role isn't listed in the actual episode's onscreen credits.
- Always Identical Twins: "A Third Act Surprise" has Oliver and Harrison Day, identical twin brothers who are both fertility doctors.
- Ambiguous Situation:
- The appearance of Sherlock Holmes in Season Two; is he genuinely visiting Watson after faking his death, or is Watson just hallucinating his friend as a result of his brain injury (obviously it is likely Holmes is alive anyway based on canon, but that still leaves it open whether or not Holmes is visiting Watson directly at this point). "A Third Act Surprise" confirms that Watson is just hallucinating Sherlock at this time. However, the real Sherlock turns up in "The Rule of Three".
- The ultimate fate of Lauren and the triplets in Watson's hallucination in "Unsolved Mysteries" is never revealed, though the fact that Stephens finds Adam alone in the waiting room instead of with Lauren strongly suggests that she didn't survive. Fortunately, Watson recovers in time to warn Adam of the danger she's in, and this outcome is prevented.
- The final scene of the series: Was the vision of Watson arriving home to Mary at 221b Baker Street a true Flash Forward, showing Watson turned out okay after surgery? Was it a dream he was having in surgery? Or was it his own personal heaven, showing he either suffered a Death of Personality or a true death?
- Amicable Exes: John Watson and Mary Morstan are separated, but they remain on friendly terms. A good thing too, considering they're frequently working together. By the end of "Patient Question Mark", Watson has come to sufficient terms with the situation that he decides not to contest the divorce, so as to make things easier for Mary.
- Anguished Declaration of Love: As Mary is about to leave Watson's sickroom in the series finale, he tells her how he walked in on her kissing Josh, and how he'd been about to tell her that he loves her and he wants her back. They have a Headbutt of Love, they kiss, Watson goes into surgery for his brain tumor, and the series ends.
- Ascended Extra: Shinwell Johnson goes from being a one-off character, to a member of the main cast.
- Asshole Victim: Played with. No one is sad about Beck's death, especially after Ingrid reveals that he had been manipulating Sasha, and Ingrid justifies his death by arguing that she did the world a favor getting rid of him. She's shocked when Lestrade refuses to give her a pass on murder, even for killing a verified asshole.
- Awful Truth: In "A Family Meal" it turns out that Wren fed herself and her brother Robin their parents' bodies to survive the Arctic where they were stranded. She lied and said it was fox meat, keeping it a secret for two decades. However, though she has been wracked with guilt over this, Robin completely understands after finding out.
- Bastard Begetter: In "The Man With the Alien Hand," after killing his brother so he can inherit the fortune of his soon to die father, Cameron is stunned when the team inform him that his father truly was the Really Gets Around type as the housekeeper's son has the same strange cleft lip Cameron has, meaning he's a product of an affair Cameron's dad had with the housekeeper. The team then drop the bomb on Cameron that he has 36 half-siblings who between them have numerous children, nieces/nephews etc. Meaning that even if the cops can't arrest Cameron, he now has a total of 68 relatives (and counting) with a claim to the family fortune, meaning that the court cases will tie up the fortune for years and Cameron will likely never see a dime.
- Bigger Is Better in Bed: In "Expletive Deleted" Sasha (who is now with Stephens) tells Ingrid he's "naturally gifted", and makes it clear from context that she means his penis size, which contributes to him being good as a sexual partner.
- Big Ol' Eyebrows: Ingrid and Sasha both have long, thick black eyebrows.
- Bitter Almonds: In the second-season premiere Dr. Watson treats a woman, his ex-wife's mother as it happens, for mysterious symptoms. It turns out that she accidentally poisoned herself with cyanide by making bitter almond extract, as confirmed by the smell of the bottle.
- Bittersweet Ending: The series finale serves as such. Mary's still seemingly off to UCLA, Sasha breaks up with Stephens owing to an accumulation of the stress she's suffered throughout the year, Lestrade is determined to prove Ingrid's guilty of Beck's murder, and it's left up in the air as to whether Watson survives his operation. On the plus side, Ingrid's finally gotten back into her therapy group, Adam is at peace being a father, and Sherlock is alive and well.
- Blackmail: In "Shannon Says Bex Loves Micah" Shinwell gets Carlin DaCosta's husband to stop dragging things out on their divorce by catfishing him then threatening that he'll disclose the explicit pics the guy sent.
- Brainy Brunette: Ingrid, Sasha and Mary are all brunette medical doctors who are very intelligent.
- Canon Foreigner: Ingrid, Sasha, Stephens and Adam.
- Chocolate Baby: In "The Tunnel Under The Elms" the white couple at the center of the story have a baby daughter named Rose who's clearly black. Though her mother swears she's been faithful, no one's sure of how this can be the case otherwise. It turns out they both have a distant, shared black ancestor and by some genetic quirk Rose came out this way.
- Clear Their Name: While investigating patient Molly Jones's family history in "Wait for the Punchline", Watson discovers her mother is Felicia Mancini, who was convicted of killing two of her children. Upon meeting Felicia in prison, Watson not only deduces the nature of the shared family condition afflicting Molly, but also realises that Felicia is in fact innocent; the condition is a rare one that could theoretically cause a person's heart to stop if they were sufficiently shocked, so Felicia's children were unwittingly scared to death by a joke Felicia made about "eating them up", Molly having only survived this long because she was taking anxiety medication. With this precedent, Watson and his team are soon working to have Felicia freed.
- Continuity Nod: Season 1's "The Man With the Glowing Chest" involves a weirdo named Hobie who has genetically engineered his chest to literally glow. In Season 2's "Never Been CRISPR'd" Hobie is back, with a girlfriend who has a medical emergency after the two of them have been doing weird gene modifying together.
- The Dandy: Watson is shown to be quite the dapper dresser.
- A Day in the Limelight:
- "Patient Question Mark" for Sasha.
- "The Camgirl Inquiry" for Stephens.
- "Take a Family History" for Mary and Ingrid.
- "Happy When It Rains" for Shinwell and Adam.
- Deadly Doctor: In "Lucky" a patient reveals that a travel nurse has been murdering patients. She's done this over several states for years.
- Deadpan Snarker: Most of the cast, especially Ingrid, Stephens and Shinwell.
- Deal with the Devil: "A Third Act Surprise" has a minor example; after Watson discovers that brothers Oliver and Harrison Day had used their position as doctors at sperm banks to illegally donate their own sperm to clients, Watson has to help give Harrison Day an immunity deal for his actions so that he will donate one of his kidneys to one of his brother's daughters.
- Death Seeker: Max is happy at being told she has cancer in "Expletive Deleted" as her rare genetic disorder which leaves her appearing to be ten has ruined her life. She gets over this after meeting another woman with the same disorder who can understand her and give her a supportive friend.
- Deceased Fall-Guy Gambit: "Teeth Marks" has an interesting variant where the Fall Guy himself knowingly confesses (albeit under duress) before dying. Watson finally starts to realise that Shinwell has been switching out his meds. Knowing that if exposed, Moriarty would probably kill his loved ones in retaliation, Shinwell decides to shoulder all the blame and pretend to be the only party involved. However, as Moriarty has further need for him, this is pre-empted by the professor having a pharmacist named Lloyd (over whom he clearly has some kind of a hold) confess to the deed in front of Watson and Shinwell, before succumbing to an overdose.
- Disabled in the Adaptation:
- Moriarty has syndactyly, resulting in his second and third fingers being fused together in a manner that makes them resemble the shape of an M. His literary counterpart had no such affliction. Ultimately averted, as it is later revealed that Moriarty was faking this condition to throw Watson off.
- Watson receives a traumatic brain injury at Reichenbach, with lingering after effects. He suffers a second one in "Wait for the Punchline".
- In Season 2, Sherlock, while he turns out to have been Faking the Dead since Reichenbach, is also sick with something that is affecting his brain, as he repeats himself and has become paranoid. While the Sherlock the audience is introduced to turns out to be a hallucination from Watson, the one who is actually sick with a brain tumor, the real Sherlock turns up with a CPX-like condition near then end of the season, both of which were caused by exposure to radiation on "The Cobalt Fissure" case.
- Earn Your Happy Ending: In "Redcoat", the team needs a surgeon willing to pull off an extraordinarily delicate, and highly risky brain operation. Ingrid enlists her former colleague and flame Isaac Niles, who believes that she is responsible for ruining his career back when they were both students. One night, he drove home after having three small drinks, but was otherwise driving steadily and responsibly. However the police pulled him over regardless, and he thinks that Ingrid tipped them off to eliminate potential competition for a grant. As a result, he lost his scholarship, racked up debt, spent time in jail, and was unable to secure work, and is now in exile in Johnstown. He ultimately agrees to the surgery, and successfully pulls off it, using unique techniques that he himself devised. His reputation is restored, and he will soon be given his pick of job offers (although he chooses a role in a different hospital to get away from Ingrid).
- Empathy Doll Shot: In "Respect the Process, Respect the Quirks", the cops come to find a little girl whose mother has been put in a psychiatric hold at the hospital. A cop whisks the child away, and the camera lingers on her stuffed animal, lying on the bed.
- "Eureka!" Moment: Watson has several, even saying the word itself in the pilot.
- Evil Hand: "The Man with the Alien Hand" involves a man with "alien hand syndrome" who wants his hand amputated because it has a mind of its own and, worse, seems to want to hurt him.
- Evil Power Vacuum: In "The Cobalt Fissure", Sebastian Moran tells Watson how after Moriarty died there has been significant infighting among his people to take his place as crime boss. Moran has been winning as he's made Holmes assist him.
- Faking the Dead: "Back from the Dead" reveals that Holmes has been doing this since Reichenbach, having wanted to get away from the pressure of being a famed detective (although this may be a hallucination Watson is having rather than the real Holmes). Double Subverted — While the Sherlock who turned up in "Back from the Dead" is a hallucination, the real Sherlock later turns up in "The Rule of Three", having faked his death but been captured by Sebastian Moran before he could reunite with Watson.
- Failed a Spot Check: "Buying Time" features the team meeting Joseph Bell, a wealthy man obsessed with longevity who has been subjecting himself to a wide range of treatments while getting his bloodwork tested on a regular basis. However, when Watson realises that his current patient, Casey Zink, was accidentally given a rare form of cancer when he was part of a clinical study run by one of Bell's shell companies, Watson realises that Bell has the same cancer as Casey; Bell's doctors never noticed because they weren't looking for the unique genetic markers of this particular cancer.
- Feel No Pain: In "The Tunnel Under The Elms" newborn Rose turns out to have congenital insensitivity to pain, though it's mild.
- Forgotten First Meeting: Somewhat applies in "Take a Family History" which reveals that Ingrid and Mary met New Year's Eve 2009/2010 when Ingrid's sister was brought into hospital with a serious spinal injury, as Ingrid asked Mary to operate on her sister to try and prevent Gigi being paralysed only for the hospital's current head surgeon to forbid the operation because of the perceived risk. It's established in the present that Mary did remember the meeting because she always regretted failing Gigi, but she didn't recognise Ingrid at first because Ingrid only introduced herself as "Didi" at the time, and when she started studying at the hospital and later working at the Holmes Clinic she concealed her and Gigi's full history so Gigi could get on a program for treating spinal injuries without Ingrid's personal connection getting in the way (it's also speculated that Ingrid deliberately doctored medical records to hide her ties to the hospital, but Ingrid counters that oversight could just mean that those specific records were lost in the transfer from paper to digital).
- Gender Flip: The canonically male Lestrade is a woman here.
- Genre Mashup: The series has been described in promotional material as a “medical drama with detective elements”.
- Glad-to-Be-Alive Sex: Ingrid goes over to Beck's place for sex at the end of "Livvy Sees the Doctor", after they've both escaped the hostage situation, and after Beck stabbed the guy with the bomb in an unsuccessful attempt to end said hostage situation.Ingrid: How'd it feel? Putting your life on the line. Taking the ultimate risk.
Beck: Felt like being alive. I wouldn't mind chasing that rush. - Groin Attack: Peter Johns in "A Family Meal" goes to the hospital for a penile fracture. He got it when his hook up, Wren, accidentally struck him in the groin.
- Hallucinations: Watson starts hearing and seeing things after he gets his meds switched with hallucinogens by Shinwell as a result of Moriarty's coercion. This includes seeing illusions of Sherlock (later hearing his voice and violin-playing) and people suddenly sporting Moriarty's syndactyly hand condition.
- Heroic Sacrifice: "Livvy Sees the Doctor" features William "Fitz" Fitzgerald taking the clinic hostage to make them examine his daughter Livvy, Fitz accepting from the start that he would even in the best-case-scenario go to prison after this was over.
- Hoist by His Own Petard: In "The Man With the Alien Hand," a billionaire's son comes to Watson pretending to want treatment for his uncontrollable hand, when what he really wants is a reputable doctor to give him a medical excuse to kill his brother and not be held responsible, so he can inherit his father's entire fortune instead of only 50%. But he ends up involving a doctor with the genetics expertise to spot the family resemblance to the housekeeper's son. From there, Watson finds dozens of additional heirs, reducing the killer's share to a single digit percentage. With his inheritance greatly reduced, the killer can no longer afford to buy his unwitting accomplice's silence, resulting in the killer getting no money and not getting away with murder.
- Hospital Gurney Scene: In "Wait for the Punchline", as Watson himself is whisked into the emergency room after collapsing (because Shinwell tampered with his meds).
- Hospital Hottie:
- Pretty much the entire team at the clinic. John, Mary, Ingrid and Sasha are quite attractive people.
- In Season 2, Watson dates Dr. Laila Bynum, a pediatric oncologist who's simply stunning.
- In "Lucky" Alicia Santos, a nurse bringing the latest case to Watson's attention, is very beautiful.
- Nurse Carlin DaCosta, who's training Shinwell, is also very attractive.
- How's Your British Accent?: In "Lucky", Sherlock places an anonymous phone call to Scotland Yard to help capture the "murder nurse". To conceal his identity from his old friend Inspector Gregson, he adopts a Scottish accent, allowing Robert Carlyle to slip into his native Glaswegian dialect.
- Hyper-Awareness: Watson learned this from Holmes. He uses his keen observational skills to help diagnose and treat patients, for instance picking up in the Pilot that two young women are actually half-sisters rather than simply first cousins by their eyes' similarities.
- I Am a Monster: In "A Family Meal" Wren thinks she's one for eating her parents' bodies, and also feeding them to her unwitting brother, since they couldn't survive the Arctic otherwise. Everyone, including Robin after finding out, assures Wren that what she did was necessary for her survival and his.
- Idiot Ball: Watson, in the “The Man With the Alien Hand." The titular man tells Watson in the beginning that he’s worried his hand could harm or kill him. The man returns to the clinic with a severe injury. Watson has acknowledged that the syndrome is rare and treatment is experimental. Despite all this, Watson releases him soon after treatment instead of restraining the patient’s hand and getting someone to observe him.
- I Have Your Wife: Moriarty gets Shinwell to fall in line by having his henchman threaten a couple he is close to.
- I'm a Humanitarian: "A Family Meal" features Wren Booker and her younger brother Robin, who were trapped in the Arctic for three months when she was 12 and Robin was 6; with limited supplies available, Wren had to use the bodies of her parents and their siblings for meat, and never told Robin the truth.
- Immortality Inducer: Joseph Bell, an entrepreneur in "Buying Time" who's obsessed with life extension, attempted to create one. It ended up giving the first test subject cancer instead, unbeknownst to both. He used it on himself as well, and dies of cancer.
- Inheritance Murder: Cameron Phipps in "The Man With The Alien Hand" murders his brother because that will leave him as the sole heir for their family fortune (at least, so it seems).
- Insanity Defense: Cameron Phipps in "The Man With The Alien Hand" sets one up by the fact he has alien hand syndrome, which means he’s not in full control over his left hand, which acts on its own at times. He makes it seem like this pushed his brother into the path of a truck without his control, which gets him off from a murder charge with Watson’s help. Soon however Watson realizes he was duped, as Cameron really intended it. He’s able to get evidence for this by the end of the episode.
- Internal Reveal:
- In "My Life's Work, Part 1" Shinwell confesses how he did Moriarty's bidding under coercion to Watson.
- In "My Life's Work, Part 2" Ingrid confesses she's the one who ruined the cultures in the previous episode. and Watson finds out not only what Moriarty looks like, but that they've met before.
- Interrupted Suicide: In "Redcoat", Andrew Tanner makes his way to the hospital roof to jump off. However, Watson had anticipated this and was waiting there to catch him before he could go through with it.
- Jack Bauer Interrogation Technique: Shinwell beat Moran into giving up information in "The Cobalt Fissure".
- Justice by Other Legal Means: In "The Man With The Alien Hand", Watson is duped into helping Cameron Phipps escape a murder charge through a fake Insanity Defense to eliminate his brother, leaving him the sole heir for the family fortune. He discovers that their father had many children out of wedlock though and notifies them, which will stop Cameron getting much if any money as they claim their shares. It's subverted at the end as well, since they get evidence showing Cameron knowingly committed murder.
- Lady Swears-a-Lot: Max in "Expletive Deleted" swears almost every time she speaks. It turns out to be a way of demonstrating she's an adult, in spite of having a genetic disorder that makes her look ten.
- Laser-Guided Karma: In "My Life's Work, Part 2", Watson uses the same Synthetic Plague research that Moriarty used on the Crofts to infect him with his own tailored virus in order to blackmail him into providing a cure for them. He then withholds Moriarty's own cure and lets him die.
- Left Hanging:
- The cancellation of the series after two seasons leaves the plot line about Watson's brain cancer unfinished, as he was going under the knife at the end of the last episode.
- Inspector Lestrade's investigation of Ingrid for the murder of her father (for which Ingrid was totally guilty) also goes unresolved.
- The last scene of the last episode has Watson returning to 221B Baker Street in London, where Mary is there to greet him. Reality? Or Imagine Spot? Who knows?
- Let's You and Him Fight: The Season 2 episode "Back from the Dead" reveals that this is the case for what happened at Reichenbach Falls in the pilot: Holmes arranged for Moriarty and Stapleton, his two biggest enemies, to both arrive at the Falls expecting to confront him and end up fighting each other instead, intending to take them both out so that he could safely go into hiding and start a new life.
- Long-Lost Relative:
- The Season 2 premiere reveals that Mary has an older brother named Miles whom she never knew about, because her parents had him before they were married and gave him up for adoption because they weren't in a position to take care of him.
- In the following episode, the adopted Sasha meets her biological uncle for the first time. However, it turns out he lied and they aren't related in "Giant Steps".
- Mama's Baby, Papa's Maybe: "Livvy Sees the Doctor" features William "Fitz" Fitzgerald taking the clinic hostage so that they will treat his adopted daughter Livvy for her unspecified illness, as Fitz has been caring for Livvy since her mother's death even though Livvy's actual father was Scott Morrison, a man Livvy's mother was having an affair with years ago. Watson later confirms that Fitz is Livvy's actual father; he and Livvy's mother slept together one night when Fitz was so drunk he didn't remember it, and she claimed that Scott was the father to get child support while aware that Fitz would be the emotionally superior father.
- Miscarriage of Justice: In "Wait for the Punchline" Watson discovers that Felicia Mancini, a woman serving a life sentence for the murder of her twin son and daughter, is in fact innocent. Her children actually died from a rare genetic disorder they inherited from her that means they can die of fright (this happened when they were bathing, resulting in drowning), which he discovers through treating her surviving daughter who also has it. Watson manages to prove this using the evidence along with the fact the original medical examiner falsified his findings for supporting a homicide, and is confident that she'll be freed soon by the end.
- Mistaken for Dying: In "Redcoat", patient Andrew Tanner believes he is dying from Huntington's Disease. Simultaneously wanting to spare himself a slow, painful death, and provide insurance money for his family, he fakes a break-in and has his accomplice shoot him in the head, although he ends up surviving the shot. Watson later realises that Andrew has not Huntington's, but Wilson's Disease; a similar, but non-fatal condition.
- My God, What Have I Done?:
- Shinwell non-verbally at the end of the pilot after he gives Moriarty the samples, and the conclusions of "Redcoat" and "The Camgirl Inquiry" when he's forced to swap Watson's medication with spiked pills.
- In "Wait for the Punchline", patient Molly Brown discovers that her imprisoned mother (whom for years she avoided visiting as she believed her guilty of murdering her siblings) is in fact innocent, and has spent that all time alone stewing in her grief and hopelessness. Molly is so overcome with horror and guilt, that she suffers a seizure.
- In "My Life's Work", Watson feels terrible when he discovers his genome research, meant to help people, has been turned into a weapon against Stephens and Adam by Moriarty. Likewise, when he finally brings about Moriarty's death, he is heavily shaken by what he's just done.
- My Greatest Failure: In "Take a Family History", Mary admits that she still regrets not being able to help Ingrid's sister Gigi avoid paralysis when the girl was brought in as a teenager after suffering serious injuries. When Ingrid confronts Mary about that in the present, Mary protests that she did the best she could when dealing with a department head who had various ego issues that meant he wouldn't accept someone else trying to undermine his authority, and in the meantime Mary assures Ingrid that Gigi can stay on her current spinal treatment program even if she makes it clear Ingrid will have to leave the Clinic for lying like that.
- Mythology Gag:
- Watson's middle name is Hamish, referencing a long-held fan theory as to what his H. initial stands for; the name was also used in previous adaptations such as Sherlock and the two Guy Ritchie films.
- Watson is shown to have penned a manuscript entitled "The Casebook of Sherlock Holmes", referencing both his primary function in the stories as Holmes' biographer, and the title of the final book in the series. By "The Camgirl Inquiry", he has started typing up more cases.
- The opening scene shows Holmes and Moriarty's iconic battle at the Reichenbach Falls. Here, rather than just learning second hand about the event years later, Watson witnesses the fight himself, and actually dives in to try and save Holmes.
- In the pilot, Watson utters two of Sherlock's iconic catchphrases: "the game is afoot" and "eliminate the impossible, whatever remains however improbable must be the truth".
- Shinwell mentions how "Holmes had the bees and the honeysnote to look after us both." In the books, Sherlock eventually retired from detection to live as a beekeeper.
- Watson nicknames the lab robot "Clyde". Clyde was the name of Holmes and Watson's pet turtle in Elementary.
- Watson's unseen Scotland Yard contact is Gregson, a character from the original stories.
- The second episode makes reference to the Baker Street Irregulars.
- The solution in "Redcoat" seems to have been inspired by "The Adventure of the Abbey Grange". Both stories feature a robbery gone wrong that is revealed to have been faked by the supposed victim, and a bottle of alcohol being divided into several glasses to give the impression of a greater number of intruders having been present.
- Watson references a medical study referred to as "The Red Headed League".
- "Wait for the Punchline" name drops Moriarty's chief henchman, Sebastian Moran.
- "The Camgirl Inquiry" mentions Irene Adler and Mrs. Hudson, with the former appearing in person in Episode 8.
- Sherlock's violin has pride of place in Watson's office.
- "A Variant of Unknown Significance" guest stars franchise stalwarts Irene Adler and Mycroft Holmes. It also name drops Baron Adelbert Gruner from "The Illustrious Client", has a visual reference to "The Bruce Partington Plans", and features Mycroft's establishment, the Diogenes Club.
- Namesake Institution: The Holmes Clinic is named after the late detective. It's not entirely for sentimental reasons, as the clinic was actually funded by Sherlock himself prior to his death.
- "Near and Dear" Baby Naming: In "A Family Meal", when Wren Booker is reunited with her estranged brother Robin six years since their last meeting, he introduces her to his daughter Gwendolyn, but reveals that they also call the girl "Wren".
- No Party Like a Donner Party: In "A Family Meal", Watson deduces that patient of the week Wren Booker is suffering from kuru, after she and her brother were the sole survivors of a plane crash in Alaska as children, and she was forced to cook their other family members' remains to keep the two of them alive.
- Not Growing Up Sucks: Discussed. Maxine in "Expletive Deleted" is 30, but looks 10. Her condition, plus losing her mother, has meant she can't hold down a job, can't date or have a family, and is never seen as the adult she is. She is so fed up she is willing to let herself die rather than keep going. At the end of the episode, she meets someone with the same genetic issue as her, who is 41 and looks even younger than Max. While it still sucks, not being alone is enough for Maxine to want to live.
- Not Quite Dead: After going over the waterfall, John is told he's the only one between Sherlock, Moriarty and himself who survived. By the end of the first episode, it's revealed that Moriarty is quite alive. In Season 2, it turns out Sherlock is alive too; the person who went over the waterfall with Moriarty was Sherlock's other nemesis, Stapelton, the detective arranging the confrontation to get rid of his two great enemies.
- Obfuscating Disability: Played with in "The Man With the Alien Hand," Watson treats Cameron, a rich man whose left hand keeps acting out of control. He's desperate to get rid of it to the point of asking Watson to amputate the hand and pours acid on it. Watson does subscribe a treatment that seems to work only for Cameron's hand to push his brother in front of a coming bus. Watson tries to defend Cameron until he discovers that the man has had major financial issues and now stands to inherit the family fortune. Watson realizes that while Cameron's "alien hand" condition is real, his killing of his brother was deliberate and he was using Watson's expertise to give him the perfect defense.
- Office Romance: The end of the second episode implies a potential budding romance between Stephens and Sasha, despite both of them already being in relationships. They get together later once their initial relationships end.
- Older Than They Look: Morris Chestnut was 55 during filming of the first season, but to look at him, you'd think he's only 35, or at most 40.
- Origins Episode: "Wrongful Life" has a series of flashbacks showing the founding of the Holmes Clinic. It turns out that there was a fifth doctor among Watson's residents, one Dr. Paola Barajas, who left the group under mysterious circumstances.
- Plot-Triggering Death: Sherlock's apparent demise serves as the impetus for Watson to leave his sleuthing career behind and return to the world of medicine.
- Professional Killer: Sebastian Moran is a hitman who worked for Moriarty, murdering an innocent random nurse just to get Watson's attention right at the start of "The Cobalt Fissure".
- Professor Guinea Pig: The episode "The Man With The Glowing Chest" has the titular character, a geneticist who figured out how to use CRISPR gene editing to make the human chest gain bioluminescence. Notably, at no point does anything go wrong with this; other than teasing from Watson, he's perfectly content with it.
- Queer Establishing Moment:
- In the pilot, Watson discerns that his ex Mary is with someone else now. She then says her partner is a woman, and not a man as he'd suspected.
- In "Teeth Marks" the patient of the week, Ginny Roberts, turns out to be queer with a girlfriend.
- In "Lucky" Lestrade turns out to be a bisexual woman when she tells Watson that she's just gotten divorced from her wife, and then starts to flirt lightly with him.
- Race Lift:
- John Watson and Mary Morstan are implicitly white in the books (and depicted as such in the illustrations). Here, they are played by black actors Morris Chestnut and Rochelle Aytes.
- Likewise, James Moriarty is played by Randall Park, who is of Korean heritage.
- Really Gets Around: The late John Phipps in "The Man With The Alien Hand" turns out to have had 36 children out of wedlock as a result of his promiscuous nature.
- Red Right Hand: The villain Moriarty has syndactyly here, having the second and third fingers of his hands fused so that they form an M like his last name. This turns out to be a fake trait Moriarty set up so that Watson would focus on an irrelevant detail.
- Reports of My Death Were Greatly Exaggerated: It's revealed at the end of the pilot that Moriarty survived the fall in the opening scene. The Season 2 premiere ends up revealing that the same is true about Holmes as well.
- The Reveal:
- In the closing scene of the pilot, it's divulged that not only is Moriarty alive and well, but he has Shinwell working for him. Additionally, the scene is preceded by a Wham Shot showing that the professor is played by none other than Randall Park.
- The Season 2 episode "Back from the Dead" clarifies what happened at Reichenbach Falls: Sherlock tricked Moriarty and another enemy, Stapleton, into fighting each other so that he could eliminate them both and go into hiding without having to worry about either of them. It was Stapleton who Watson saw go into the water with Moriarty, and Sherlock who pulled Watson out afterwards.
- "A Third Act Surprise" concludes with the revelation that Sherlock has been a hallucination all along.
- Two episodes later, it's revealed what's been causing it: Watson has a brain tumour.
- "The Rule of Three" ends with the discovery that Sherlock really is alive after all, albeit in a very poor cognitive state.
- Running Gag: Watson keeps forgetting to add the s to Stephens' name, referring to him as "Stephen…zzzz".
- Screw the Rules, I'm Doing What's Right!: In "The Man With The Glowing Chest", Watson determines that the best way to deal with his current patient's acute sickle cell disease is to have a geneticist associate (the titular character) come in and perform an unauthorized and unapproved gene therapy treatment on her, which he admits is illegal and likely to cost him his job if anyone finds out about it. When asked why he's doing it, he justifies it by stating that it's the morally right thing to do. The fellows figure out what he's doing, but ultimately agree with his decision for the same reason, and Mary also figures it out later, and likewise keeps quiet when she sees how well it's worked.
- Secretly Wealthy: Unbeknownst to Watson, Holmes had quite the hefty bank account, and used it to fund the clinic.
- Separated by a Common Language:
- In "Teeth Marks", Shinwell comes in to the office and mystifies Watson with some British slang.
Shinwell: Feeling pucker, guv?
Watson: Am I feeling...pucker.
Shinwell: Vigorous.- Then seconds later this is reversed.
Watson: This current dosage is having me feel a little wonky lately.
Shinwell: "Wonky." That's a scientific term, is it?- In "Shannon Says Bex Loves Micah", this is a gag when Shinwell the trainee nurse is talking with his supervisor Carlin, who makes a joke about the once-criminal Shinwell breaking thumbs.
Shinwell: Do you know, I never once broke a man's thumb. Not once in all me puff.
Carlin: "All me puff?" I love it when you talk ridiculous.
Shinwell: Oh you think yinz guys are in a position to judge who sounds silly, do you? - Shell-Shocked Veteran: In "The Dark Day Deduction" Watson treats a former soldier he served alongside in Afghanistan who's suffering from PTSD due to having survived a Suicide Attack. Watson feels guilty about this, since his treating an Afghan woman there delayed the withdrawal of their unit and made them all vulnerable to the attack.
- Sherlock Scan: As to be expected for a Holmes adaptation, although this time, it's Watson doing them.
- Sound-Effect Bleep: Every time Max swears in "Expletive Deleted" (which happens very often) this is covered by a cartoonish sound effect and graphic over her mouth.
- Special Guest: Randall Park is credited as one for playing Moriarty.
- Surprise Pregnancy: In "Happy When It Rains", Adam's fiancee springs it on him that she's pregnant, which neither of them planned. He says he's happy, though privately Adam admits this isn't true - though this makes him feel guilty, he isn't pleased at the idea of being a father. And things get even worse in "A Family Meal" when it turns out that the pregnancy is triplets, adding to the pressure that Adam feels to provide for them.
- Synthetic Plague: In "My Life's Work, Part 1", Moriarty uses Watson's genetics research to create a tailored virus that infects Adam, who overheard something that might endanger Moriarty's plans. Given their shared DNA, Adam's identical twin brother Stephens gets infected too, as they tend to drink from the same coffee mug. Watson turns the tables on Moriarty after this in the next episode, "My Life's Work, Part 2", by infecting him with a virus tailored to only affect Moriarty's DNA so he'll deliver the cure for Stephens' disease in return for being cured himself. To stop him from harming other people, Watson does not give Moriary the cure and lets him die.
- Talking Down the Suicidal: In "A Family Meal" Wren nearly kills herself as she's wracked with guilt over resorting to cannibalism for her and her brother Robin to survive the Arctic. Ingrid has to talk her down, pointing out that a real monster, as Wren thinks herself to be for this, wouldn't feel such intense guilt.
- That One Case: "Unsolved Mysteries" features Watson experiencing a coma fantasy where Sherlock and the fellows try to diagnose the cause of death of Malcolm Anson, Watson's old medical mentor and would-be best man, who died on the day of Watson's wedding from a disease Watson has never been able to diagnose. With Anson's daughter currently in hospital, for apparently the same condition, Watson is able to diagnose her father's condition and save her life.
- Time-Passage Beard: In the opening scenes when Watson is lying unconscious at the hospital, the passage of weeks is demonstrated by sped up footage of his neatly trimmed beard growing out to become thick and unkempt.
- Trauma-Induced Amnesia: As a result of his head injury, Watson initially has little recollection of the weeks leading up to Reichenbach. Thus, he is unable to recognise Moriarty on sight, although he does remember he had a syndactyly which turns out to have been a fake detail Moriarty adopted to throw off later attempts at identification.
- Tragic Stillbirth: In "Teeth Marks" it turns out that just after Watson had left for Reichenbach, Mary had fallen pregnant with their baby daughter, but miscarried. She didn't tell him as they tried unsuccessfully for years to have a baby, and Mary didn't want him feeling the devastation of losing her too.
- The Watson: As expected for a show about the trope namer himself. However, the role is filled not by the good doctor, but by his surgical team, who are not used to his very specific deductive methodology.
- "Well Done, Son" Guy: "Giant Steps" reveals that Watson has a strained relationship with his father Hamish, due to having not been able to live up to his father's musical talent and demanding attempts at mentorship.
- Wham Shot:
- The ending for "A Son in the Oven" where Watson overhears an intruder in his apartment, going through his fridge. The doctor picks up a cricket bat and approaches only to recognise him:
Watson: Sherlock?
Holmes: (turns around and gives a delighted smile) My dear Watson!- The ending of "A Third Act Surprise" reveals that the Sherlock Holmes that Watson has been seeing for the last few episodes is actually a hallucination.
- What the Hell, Hero?:
- A downplayed case in the Season 2 premiere, where Shinwell calls out the Fellows for suspecting Ingrid has ulterior motives for her return to UHOP, when she's already freely confessed and paid the price for her actions in the previous season.
- In "Back from the Dead", Watson chews out Holmes for letting him think for a year that he was dead.
- You Are Better Than You Think You Are: In "A Family Meal", when the team determine that Wren Booker's current illness is because she ate the remains of her parents while she and her brother were trapped in the Arctic for months after a plane crash, she attempts to kill herself out of the over two decades of guilt she felt over that act, considering herself nothing but a monster. Ingrid is able to talk her down, assuring Wren that if she was a monster she wouldn't have been dealing with this guilt for so long.
- You Did Everything You Could: Upon hearing of Sherlock's demise, Watson blames himself for failing to save him. Shinwell immediately shuts this down.