Tommy is the 12 year old son of an ultra competitive family. His father, mother, and little sister Darleen are all obsessed with winning. However, Tommy has always lost at everything. He gets sent to winner Island Camp, where they guarantee that the children sent there will return a winner. However, as Tommy checks the brochure, it seems more like they mean that the children who lose won't come back at all. He arrives at the camp and sees that all the kids in the camp are ultra competitive. After his duffel bag is stolen by a man named Robb, Tommy soon learns from a girl named Sophie that everyone is competitive because the island is home to Mrs. Maaargh, a grotesque, fat monster who serves as a teacher. But more importantly, she keeps a list of the campers that she ranks based on performance. And whoever is at the bottom of the list by the end of the summer will be the one she'll eat. Tommy is skeptical about all of this until he meets Mrs. Maaargh. And after his meeting doesn't go well, he's placed on the bottom of her list.
Tommy tries to escape, but there's no hope in doing so. He tries to compete in the various challenges given by Mrs. Maaargh, but always fails. Be it of his own volition, or because his fellow campers Sophie and Ricardo constantly lie to him and set him up for failure. Tommy eventually finds his duffel bag, which includes a bottle of hot sauce that his family enjoys. Eventually, Tommy ends up failing at every challenge, making him the camper at the bottom of the list. He's about to be eaten by Mrs. Maaargh, when suddenly she starts to choke. While licking him, she tasted the bottle of hot sauce in his pocket. She panics and swims off the island. The kids celebrate, until Uncle Felix, the camp director, introduces a two-headed monster named Mr. Baaargh as their new camp teacher who now plans to eat the bottom two campers on the list.
Tommy is a rather good-natured kid. He's above average at most things, but isn't much of a winner, which is why he's sent to Winner Island Camp. He also is very skeptical, not willing to believe anyone about Mrs. Maaargh until it's too late.