In the magical, fog-shrouded underworld of Victorian London, Tessa Gray thought she had finally found safety with the Shadowhunters. But that fragile security shatters when it becomes clear that the mysterious Magister will stop at nothing to capture her and use her unique powers for his own dark ends. Supported by the handsome, tortured Will and the fiercely devoted Jem, Tessa discovers that the Magister's war against the Nephilim is fueled by a deeply personal revenge. To unravel the secrets of the past, the trio must journey from the bustling streets of London to a mist-shrouded manor in Yorkshire that holds untold horrors. As they face down terrifying clockwork demons and uncover a traitor in their own ranks, Tessa finds her heart increasingly torn between Will and Jem. In a world where secrets and lies can corrupt even the purest heart, Tessa must discover who she truly is before the Magister destroys them all.