Being allies does little to discourage Moscow from recruiting double agents in the British establishment. The most famous of them all, Kim Philby and the Cambridge Five, penetrate deep into MI5, MI6, and Bletchley Park. With friends like the NKVD, who needs enemies?

The NKVD have wormed their way into British society. Across the pond, America is also teeming with communist spies. They're in the government, military, even OSS, and the FBI. Now they're going for the biggest secret of all – the atomic bomb.