In the magical underworld of Victorian London, Tessa Gray finds her heart drawn more and more to Jem, though her longing for Will, despite his dark moods, 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 the answers about who she is and what she was born to do? As their dangerous search for the for the truth leads the friends into peril, Tessa's heart is increasingly torn, especially when one of their own betrays them...