Broadcast: Nov. 11- 25, 1973 David Foster, a technical installation director, is about to take an important post in NATO when British Counter Intelligence is tipped off about a plot to replace him with a substitute. This may have already been done. At a frontier post between East and West Germany, the real Foster is interrogated by Captain Mason, while his car is searched. Gregory who is to take his place, is still receiving a final polish and a decision is made to make it appear Foster is going through a period of instability. Then, when Gregory takes over after Foster's murder, any uncharacteristic behavior will pass unnoticed.