Jeremy hates his new house. His parents are so obsessed with keeping everything spotless that he can't have friends over, can't play in the yard, and definitely can't have a pet.

Then he finds a strange egg in his cousin Kate's backyard. It's far too big to be a tortoise egg, and the wrong colour entirely. But Jeremy doesn't care. He buries it in the compost bin and waits.

What hatches is unlike anything he's ever seen: a mottled, scaly creature with spiked ears, bright green eyes, and an insatiable appetite for rubbish. Jeremy names him Ulp.

Keeping Ulp secret is hard enough. But when Jeremy gets picked for the school football team and needs sixty dollars for proper boots, he and Kate must find a way to earn the money fast, all while hiding a rapidly growing mystery creature who's getting harder to conceal by the day.

Every dollar they earn, Ulp eats a little more. Every day that passes, the compost bin fits a little less.