A Russian probe bound for Mars falls in the U.S. Oscar and Steve and Oscar nab a trio of spies intent on covering up the event. Then they learn a couple pretending to pose as a married pair stayed at a hotel and are following the machine. Steve saves the woman and discovers she's in fact an old friend, Irena Leonova. She accounts for the purpose of the probe and how it has become a killing machine. Now Steve must stop the apparatus.
Episode number: 4x14 Production Number: 45122 Airdate: Sunday January 09th, 1977