The C.I.A. discovers a Russian plot to assassinate five defectives on the Christmas Day, but they do not know who they are. The defective Alex Holbeck is recruited in Paris by the C.I.A. and sent to East Berlin to steal the scrambler of the Enigma, the machine used by Soviet intelligence for communication. On arrival, Holbeck discovers that the K.G.B. and the East German government know that he has arrived and his contacts are arrested. Holbeck meets his former lover, lawyer Karen Reinhardt, and she gives him a safe house. Russian Agent Dimitri Vasilikov and East German Agent Kurt Limmer try to find Holbeck's whereabouts using different methods, while Karen seduces Dimitri to get the information about the location of the soldiers that Holbeck needs. However, Holbeck does not know that the C.I.A. has the scrambler, and he is only the bait to convince the Russians that they do not have it.