From New York Times bestselling author Justina Ireland and Tessa Gratton comes the first book in a ferocious YA fantasy duology featuring ancient magic, warring factions, and a romance between the two people in the world with the most cause to hate one another.

Darling Seabreak cannot remember anything before the murder of her family at the hands of House Dragon, but she knows she owes her life to both the power of her Chaos Boon and House Kraken for liberating her from the sewers where she spent her childhood. So when her adoptive Kraken father is captured in battle, Darling vows to save him--even if that means killing each and every last member of House Dragon.

Talon Goldhoard has always been a dutiful War Prince for House Dragon, bravely leading the elite troops of his brother, the High Prince Regent. But lately his brother's erratic rule threatens to undo a hundred years of House Dragon's hard work, and factions are turning to Talon to unseat him. Talon resists, until he's ambushed by a fierce girl who looks exactly like the one his brother has painted obsessively, repeatedly, for years, and Talon knows she's the key to everything.

Together, Darling and Talon must navigate the treacherous waters of House politics, caught up in the complicated game the High Prince Regent is playing against everyone. The unlikeliest of allies, they'll have to stop fighting each other long enough to learn to fight together in order to survive the fiery prophecies and ancient blood magic threatening to devastate their entire world.