Tessa discovers that the magister's war on the shadowhunters is deeply personal. to unravel the secret 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 real ize that 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 search leads to deadly peril, Tessa learns that secret and lies can corrupt even the purest heart.