U.S. Marine veteran Mason Hackett moved to London to start his life over, and he’s done his best to convince himself that what happened 15 years ago doesn’t matter --- the people he killed, the men he lost, the lives he ruined. But when Mason sees the face of a dead friend flash on a television screen and then receives a mysterious email referencing a CIA operation gone bad, no longer can he ignore his inner demons.

Driven by loyalty and a need to uncover the truth, Mason launches on a perilous journey from the Czech Republic to Romania toward the war-torn separatist region in eastern Ukraine to honor a 15-year-old promise. The answers he seeks --- the fate of a friend and his connection to the underworld of international arms dealers and defense corporations --- throw Mason into the cauldron of a covert war where no one can be trusted.