In dazzling Regency London, married spies Malcolm and Mélanie Rannoch find their most challenging investigation may be uncovering the secrets of the cunning spymaster who shaped both their destinies.

Spymaster. Revolutionary. Master of disguise. Raoul O'Roarke remains an enigma even to those closest to him. By the age of three, Malcolm Rannoch knew enough of Raoul's life that he wondered if every goodbye would be their last. Thirty years later, Malcolm, now a spy himself, understands a great deal more, but in many ways Raoul is still a mystery. Malcolm's wife and fellow agent Mélanie has her own complicated relationship with Raoul, who was once her spymaster.

When a contact at a dockside tavern warns the Rannochs that powerful forces want Raoul dead, Malcolm and Mélanie are shaken to the core. They've barely had time to absorb the revelation when a nearby ship explodes. Rushing to help fight the ensuing fire, the Rannochs find the body of the powerful Duke of Bamford amid the charred wreckage.

Bamford, a Tory diplomat and Raoul, a revolutionary, knew each other far better than anyone realized. Their unlikely alliance leads from the French Revolution through Napoleon and Josephine's glamorous court to the glittering Congress of Vienna, and the horrors of Waterloo. The clues from their past hold the key to Bamford's murder. As Malcolm and Mélanie connect the pieces, they find as many questions as answers. Raoul has even more secrets than either of them guessed-secrets they need to uncover to prevent his meeting the same fate as the duke. But the process may shake their relationships with him to the core. And their next goodbye could be their final parting.