From the #1 New York Times bestselling author of Lore and The Darkest Minds trilogy comes the high-stakes YA fantasy of the year! With a tenacious heroine, deep roots in Arthurian legend, and a breathless chase from Boston to Cornwall to mythical Avalon, this book is pure adrenaline.

Seventeen-year-old Tamsin and her brother Cabell are treasure hunters. Abandoned by their guardian as children, they seek legendary relics from the vaults and tombs of dark sorceresses. But if they can't find the magic to break the wicked curse on Cabell, it will soon erase every last trace of his humanity.

When Tamsin learns her guardian disappeared with a ring capable of breaking any enchantment, they know they must find him before their rivals, including the charming Emrys, who has a secret of his own.

The search leads them across modern-day England into Avalon, but the misty otherland is nothing like legends claim, and its deadly surprises force Tamsin and her brother into an uneasy alliance with Emrys and an apprentice sorceress just to survive. As the mystery rotting the heart of Avalon consumes them, and they come no closer to finding the ring, Tamsin begins to fear she won't just lose her brother - she'll lose her one chance to uncover the secret of who she truly is.

For fans of Holly Black, Cassandra Clare and Legendborn.