Alex Holbeck (Martin Sheen) is recruited as a CIA agent. He is sent to East Berlin on a mission to steal an Enigma code scrambler. This is part of an attempt to stop the Russian assasination of five Soviet dissidents which is planned for Christmas Day. What Alex doesn't know is that the CIA already have a code scrambler. By stealing the scrambler in Berlin, they are trying to convince the Russians that they don't have it.
On arrival in Berlin, Alex finds that the KGB know he is there. Alex must use numerous disguises and escape from a number of capture attempts. He seeks shelter with his former lover, Karen (Brigitte Fossey) before moving on as this is too dangerous for her. Karen and a number of Alex's other old friends are taken and assulted by the police in an attempt to gain information about Alex's whereabouts. As he gets more desperate, Alex enlists Karen's help again: she seduces Dimitri Vasilikov (Sam Neill), the KGB man in charge of the hunt for Alex, in order to obtain information. In the end Dimitri catches Alex and Karen and finds the scrambler hidden in an exhibition artifact. As he is in love with Karen, he lets them go, however, keeping the scrambler which was in fact not needed. On Christmas Day the assassination attempt is successfully thwarted.
