Copper Roland is just an ordinary sixteen-year-old girl living in Muddon, until she sees a horrifying troll, called Jalzubuck Foul, climb in through her bedroom window.
Jalzubuck, who is built like a potato filled with rocks and smells like grated dead fish smothered with sauce made from rotten garbage, sings a song about making little girls into meatballs.
Copper tricks the troll into falling out of her window by telling him that there are child-brain soups outside. She realises that the troll has to be stopped before he eats any more children and sets to work trying to invent a trap.
Meanwhile, in a cave just outside Muddon, Flitty Boggerton starts to suspect that eating children is wrong, and grows tired of hunting with her fellow trolls. She decides to live as a vegetarian.
After a brief misunderstanding involving a toe and lashings of ketchup, Copper and Flitty team up to stop the trolls, using a catapult that fires tomatoes. They lure the trolls by creating a big mound of earwax.