Caitlin is the only young person living on Middle Island. On the first day of vacation, she finds a tiny alien on the beach. Caitlin becomes close to her secret friend, whom she names Perijee, and treats him like a brother. Caitlin has a reading disability, but finds she is a good teacher, telling Perijee everything she knows about the world.

There's only one problem: Perijee won't stop growing. And growing . . . Caitlin will have to convince the adults around her--and Perijee himself--that the creature they see as a terrifying monster is anything but. When things get out of hand, brave Caitlin embarks on a journey to save Perijee before it's too late.

Praise:
"Elements of humor and an attractive jacket add to this chapter book's undeniable appeal." --Booklist

"A cute read for kids who like a strong dose of absurdity." --School Library Journal

"Montgomery's jam-packed narrative doesn't slow for an instant in this exaggeratedly comic drama. . . . Humor carries the day." --Kirkus Reviews

"Caitlin's desperation for friendship is palpable, and the book powerfully conveys the longing for connection that drives her to risky actions. This British import is earnest, often quietly thoughtful, and quirky." --The Bulletin of the Center for Children's Books

"Montgomery engages us with . . . high drama, hurtling towards a heartwarming resolution." --The Sunday Times (London)