Checkmate, My Lord

Checkmate, My Lord is a historical romance by Tracey Devlyn, published by Sourcebooks Casablanca in 2013 and the first of her Nexus novels.

Sebastian, Lord Somerton, is a spymaster: he runs the Nexus, a secret organisation operating under the cover of the Alien Office, and his work has caused a great many deaths without him ever having betrayed his country. In the upheaval that follows the kidnapping and abuse of his former ward, he is accused of treason and required to step down from his duties and hand his superiors a list of all his people, with their names, code names and locations, so that he can be cleared. He has sworn never to give them up, and he cannot be sure whether his refusal is prudence or paranoia. The widow of one of his agents, Katherine, Lady Ashcroft, has her own interest in the case, and the two of them end up investigating the same betrayal from opposite directions.

Devlyn writes romance inside a spy plot, and the novel's tension comes from two people whose loyalties are already committed elsewhere.