It's spring break, and the pretty little liars are trading in Rosewood for a cruise vacation. They want nothing more than to sail into the tropical sunset and leave their troubles behind for one blissful week. But where Emily, Aria, Spencer, and Hanna go, A goes, too. From scuba diving to tanning on the upper deck, A is there, soaking up all their new secrets.

Emily is smooching a stowaway. Aria's treasure-hunting partner is a little too interested in her booty. Spencer's going overboard trying to land a new boy. And a blast—or rather, a crash—from Hanna's past could mean rough waters ahead for everyone.

The liars better tighten their life jackets. A perfect storm is brewing, and if they aren't careful, A will bury them at sea. . . .