Sebastian St. Cyr, Viscount Devlin, is asked by the Archbishop of Canterbury to help in the investigation of two corpses found in an ancient crypt, their violent deaths separated by decades. One is the Bishop of London, the elderly Archbishop's favored but controversial successor. The identity of the other seems lost in time.

Sebastian amasses a list of suspects that range from some of the Prince Regent's closest cronies to William Franklin, embittered son of famous American patriot Ben Franklin - and finds himself confronting the well-guarded secrets of his own family's history. Now each step he takes toward the killer brings him closer to a devastating truth that could ultimately force him to question who - and what - he really is.