IN THE MAGICAL UNDERWORLD OF VICTORIAN LONDON, Tessa Gray has found safety with the Shadow hunters. But when Charlotte's position as head of the London Institute is threatened, Tessa could become easy prey for the mysterious Magister, who will stop at nothing to use Tessa's powers for his own dark ends.
With the help of handsome, tortured Will and the devoted Jem, Tessa discovers that the Magister's war on the Shadow hunters is deeply personal. To unravel the secrets of the past, the trio journeys from mist-shrouded Yorkshire to a manor house that holds untold horrors. When they encounter a clockwork demon bearing a warning for Will, they realize that the Magister knows their every move-and that one of their own has betrayed them.
Tessa is drawn more and more to Jem, though her longing for Will continues to unsettle her. But something is changing in Will-the wall he has built around himself is crumbling. Could finding the Magister free Will from his secrets, and give Tessa answers about who she really is? As their search leads to deadly peril, Tessa learns that secrets and lies can corrupt even the purest heart.