Meet Ista Flit. Daughter. Face-changer. Thief . . . Amongst the cobbled streets and misty alleyways of Shelwich, magic rises and falls with the Tide. When the Tide is out, the magic ebbs to a low murmur.
When the Tide is in, the magic is high - and Tide-blessings are at their strongest. For most people, the Tide-blessing they are born with is nothing more than a simple party trick: eyes that change colour, or the ability to recite a poem backwards. Some, though, are blessed with more powerful gifts.
Telepathy. Flight. Or, in the case of Ista Flit, being able to transform to look like someone else.
Anyone else... Ista has come to Shelwich in search of her missing father, and she'll do anything to find him - even work for Shelwich's most notorious thief. Then she meets Nat and Ruby, both struggling with their own search: Nat for his little brother, Ravi, and Ruby for her sister Saf.
As more strange disappearances send shockwaves through the town, they must form a tentative friendship and draw on all the Tidemagic they can to unravel a mystery that leads to an old, abandoned theatre, and to the ancient caves beneath Shelwich. But what they find there will be far more than they have bargained for...