1949. The Cold War is intensifying and rumours abound that the Russians are close to creating an atomic bomb. Beattie Cavendish, special operative for a covert section of GCHQ is sent to Scotland, to a listening station in the Highlands at Kilbray. Beattie's arrival is greeted with suspicion by the station's staff. She faces an uphill battle to turn things around. When Beattie discovers that her uncle Howard, who lives nearby, has gone missing, she becomes convinced his disappearance is more sinister. She learns Howard has been visiting a remote Highland lodge used during the war to hide out of favour special operation executive officers. As she delves deeper, there is no one she feels she can trust except for private detective Patrick Corrigan.

But Corrigan has troubles of his own as he needs to get out of London after crossing the Kutsnetsov brothers, a pair of notorious Russian gangsters. As the snow begins to fall hard and fast, Beattie realises the search is putting her life and that of Corrigan's in danger, and that the answers she is looking for lie buried in her wartime past.