The Seventh Floor — David McCloskey

Six CIA officers. Dear friends and cherished enemies. For a quarter-century they have stolen other people's secrets. Now they must steal each other's.

A Russian arrives in Singapore with a secret to sell. When the Russian is killed and Sam Joseph, the CIA officer dispatched for the meet, goes missing, Artemis Procter is made a scapegoat and run out of the service. Traded back in a spy swap, Sam appears at Procter's doorstep months later with an explosive secret: there is a Russian mole within the upper reaches of the CIA. As Procter and Sam investigate, they arrive at a shortlist of suspects made up of both Procter's closest friends and fiercest enemies. The hunt requires Procter to dredge up her checkered past in the service of CIA, placing the pair in the sights of a savvy Russian spymaster who will protect Moscow's mole in Langley at all costs.