Home after Napoleon's defeat at Waterloo, Clemency, Countess of Ashford, looks forward to resuming a quiet life. But her past refuses to stay in the past. Fighting memories, the Extraordinary Mover takes to the skies by night, secretly bringing criminals to justice.

When a rash of bombings strikes London, the crisis entangles Clemency in the intrigue centered on the bomber's terrible demands: remove all Extraordinaries from their positions of power, or the city will burn. As Clemency pursues this most dangerous criminal, her past and present collide, forcing her not only to save London, but also to save herself.