Cordelia Carstairs, a Shadowhunter trained to battle demons, travels with her brother to London where they reconnect with childhood friends but soon must face devastating demon attacks in the quarantined city.

"Like a bolt from the blue, Jack's little sister Maddy is gone--carried into another realm by an ogre. When Jack and Lilly follow Maddy's captor through the portal, they are ready for anything . . . except what they find waiting for them in the floating crossroads between worlds. Even the power of their magic plants may not be enough to get them back to earth alive. Alone and injured, Jack and Lilly must each face their own monsters--as well as giants...