Jordan Keppler and his sister Karla are spending a day at Carnival World. There, they discover a strange attraction — Robby, a boy in a cage, begging for food, while a sign on the cage forbids them from doing so. Unfortunately, Jordan and Karla don't obey. And as a result, they find Robby turns into a vicious monster whenever he eats... and now that he's on the loose, they must find a way to trap him again before it's too late.
This book provides examples of:
- Abusive Parents: Robby claims to have one, saying he was thrown into a cage as a cruel joke. He's lying — the man who put him there is not his father, and he was thrown in there due to being actually dangerous.
- Adults Are Useless: Surprisingly averted. The parents believe the kids about the monster, at least try to fight it, and eventually help the kids with their plan to take care of it.
- Big Eater: Bernardo, one of Jordan's classmates, who's always eating.
- Covers Always Lie: A lighter example. The cover has Robby in a wooden crate while in the book he is in a roomier cage made of metal.
- Cruel Twist Ending: Jordan is mistaken for the monster and is captured.
- Faux Affably Evil: Robby pretends to be an innocent person while in human form, swearing he won't turn into a monster again. Of course, each time it's an act and he keeps turning into a monster after being fed.
- Malicious Misnaming: Karla has a habit of mockingly calling Jordan things like "Jerkface".
- Vomit Indiscretion Shot: Robby has the tendency to vomit orange stuff after he goes into his monster form.
- Voluntary Shapeshifting: Robby's entire shtick. He has the power to become anyone, although his default human form is that of a boy. He becomes other people to trick them a few times.
- Title Drop: The kids first see Robby in a cage that has a sign on it that says Please Do Not Feed the Weirdo.