New York Times bestselling, acclaimed horror author Paul Tremblay delivers an unforgettable middle grade debut in this bone-chilling tale of an unsettling, unbreakable friendship.

"All the questions we ask as kids about who we are and what we're worth take a terrifying turn in this spooky tale of a sinister, inhuman imposter and the nightmares he brings. Tremblay has taken the world of horror for adults by storm, and in his middle-grade debut, once again, he serves up scenes that will make you squirm long after the book is closed."

—M.T. Anderson, National Book Award Winner

When Casey Wilson's parents tell him that his friend is coming for a sleepover, he has no idea who that might be. Ever since the Zoom Incident, everyone treats him like a pariah, and his tics are worse than ever.

When Morel appears, he's not like any friend Casey has ever met. His skin is like clay, and he doesn't speak. But Casey's parents are charmed by the strange kid, and it's nice to have someone to talk to besides his sister, Ally, who is away at college. As his normally loving parents grow distant from Casey, they gush and fawn over Morel. Casey knows something is wrong—but with no end in sight to the sleepover, he's exhausted. And in the dark, out of the corner of his eye, Morel doesn't look like a kid at all. . . .