Living in the small town of East Thumb, Maine, upstairs from her family's diner, twelve-year-old Lizzy Sherman searches for signs to guide her and perhaps guarantee her a bump-free path through life. She pays attention to the clouds in the sky, the ice cubes in her water, the heart-shaped puddle of the juice her friend spilled. If only she can figure out what the signs are trying to tell her, she'll know what to do next.

When Lizzy and her best friend go searching for a stray cat and find a runaway girl instead, they want to help. And when Lizzy notices a tiny four-leaf clover tattooed on the girl's hand, she knows it's a sign. Lizzy hides the girl inside her bedroom closet, convinced the girl will be able to protect Lizzy's family from tragedy. But signs can be tricky, and what the girl has to offer may be more valuable that luck.