A bewitching and powerful tale of sparkling magic, spellbinding mystery and a friendship worth risking everything for, perfect for fans of Tamzin Merchant, Abi Elphinstone and Anna James. Several months after the Frost Fair cast its spell over London, best friends Thomasina and Anne are running their own sweet shop – and, truth be told, longing for adventure again. Then the rumours begin – rumours of unexplained storms and catastrophic shipwrecks.

And then disaster strikes, and their beloved friend Henry disappears: snatched by a mysterious creature, and dragged down into the depths of the River Thames. Determined to save him, the girls venture into the deep, and discover the enchanting world of the Free Waters: a vast, glittering underwater city, home to mermaids and sirens. But the Free Waters are threatened by a monstrous and terrifying evil: the Sea Queen.

It is she who has Henry in her clutches – and the girls must complete three treacherous and impossible magical tasks if they are to save his life . . .

An unputdownable and exciting new tale from the bestselling author of The Miraculous Sweetmakers: The Frost Fair.