Spymaster and head of the Nexus, a super-secret organization under the aegis of the Alien Office, Sebastian, Lord Somerton, is responsible for many men's deaths, but he has never been a traitor. Nevertheless, in the upheaval following the kidnapping and abuse of his former ward, Cora, also known as Raven, he is accused of being a traitor, and must both step down from his duties, and provide a list of all his people, names, code names, and locations, to his immediate superior in order to be cleared. With the obvious double-dealing and traitors in their midst, He has vowed never to give up the names of his people, but now he must decide if he is being wise or too paranoid. What will happen to them if he dies?

In the midst of this quandary, the widow of one of his men, Katherine, Lady Ashcroft, brings him letters Ashcroft should not have sent her prior to his death, full of ciphers, and obviously intended for him. She demands to know why his name is sprinkled through these letters with their confusing passages, and what they mean. Refusing to be fobbed off with stories of footpads, she demands to know how her husband died, and why.

Sebastian cannot tell her, for the fate of all of his people may be at stake. But she has secrets she cannot tell him, and the end result of all these secrets may be the deaths of those they hold dear.