The City - mankind's last refuge in a drowned world, where Whale Lords reign and the Inquisition keeps the peace.The Enemy - a dark power, ever seeking to take possession of a human body and cause untold chaos.The Inventor - a girl living in the heart of the City in a ramshackle workshop overflowing with curiosities.When a whale washes up on the City roofs and a mysterious boy emerges from its belly, the superstitious citizens assume the Enemy has come again. Only Ellie - a fearless inventor striving to live up to her mother's legacy - believes the boy is innocent. Thrown together with the young fugitive, now on the run from the ruthless Inquisition, Ellie must discover who this boy really is - and what that means for her own terrible secret . . .