There's a whole world out there and it isn't ours!

The words of her mentor inspire Kali Hooper to explore the lost places of Twilight, unearth the secrets of its past and discover the fate of the vanished Old Races. But when an unexpected encounter in the deadly Spiral of Kos brings Kali head to head with Twilight's all-consuming Final Faith, she finds herself in a race for the keys to the Old Races' most terrifying secret yet the mysterious construct known as the Clockwork King of Orl.

Everything Kali knows is about to change. She'll lose old friends, gain new ones, learn a devastating secret about herself, and come face to face with a threat she must stop at any cost. Because while the Final Faith believe what they are about to unleash is their true destiny, Kali knows it is not only their future but the whole of Twilight's that hangs in the balance. She has seen the fires, the deaths. She has heard the marching. The marching that heralds a sea of blood...