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, teaching him everything about her world and treating him like a brother. 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.