Magic, mystery, and monsters abound in this series opener about a girl with the rare magical ability to look like anyone she's ever seen. Now in paperback!

In misty Shelwich, magic ebbs and flows with the tides, granting the citizens extraordinary abilities every time the river rises. But people are disappearing...and rumor has it they are being snatched by monsters.

Ista Flit doesn't want to believe it. Not when her own father is missing. As she scours the city, searching for clues, a notorious thief finds her. Ista has a rare talent: she's a face-changer, able to take on the appearance of anyone she's seen, and Alexo could use a girl with her skill. Ista could use Alexo's help in her search--if only she could trust him.

As more people vanish, Ista finds unexpected allies in Nat and Ruby, each searching for their own missing loved ones. These three determined kids will need to use all the Tidemagic they can summon, to find out what connects thieves, monsters, and the missing. But they have no idea what dangers await them in the hidden labyrinth of caverns deep benearth the city streets...