In the aftermath of the failed assassination attempt on Adolf Hitler, a Berlin police superintendent tries to unravel the meaning of a mysterious message transmitted by a British spy moments before he is killed. British Intelligence thinks the message might be offering the Allies information about Germany’s progress in building an atomic bomb. An American air force captain is the key to obtaining it, because the message might be from his ex-fiancée. The problem is, the ex-fiancée is a heroine of the Reich and the daughter of a prominent Nazi tycoon, and the American captain is a prisoner in Germany’s highest-security P.O.W. camp, Colditz Castle. The NKVD, the Russian Secret Service, also desperately want the atomic bomb information and are willing to do whatever it takes to get it. The deadly race is on.