Screenplay by BRIAN CLEMENS   Directed by ROY WARD BAKER     Nemesis agents find themselves programmed to kill their own colleagues—and two of the Champions come to blows.     What has happened to George Brading (RICHARD OWENS)? He is a trusted and long-established Nemesis operator. After a two-day disappearance, he returns to the Nemesis building, walks straight up to a senior official and kills him.   There is no explanation except for the discovery that he has been given a powerful drug and, unless it can be identified, there is no way of administering an antidote. His wife Loretta (RACHEL HERBERT) avers that there was nothing unusual about his behaviour when he left home except that he was worried at losing his briefcase.   Craig Stirling (STUART DAMON), Sharron Macready (ALEXANDRA BASTEDO) and Richard Barrett (WILLIAM GAUNT) investigate and learn from a garage mechanic that Brading had received news that his case had been found and went off with the police to recover it.   The next chapter in the strange events is when Nemesis boss Tremayne (ANTHONY NICHOLLS) disappears for a whole afternoon. When he returns he, too, is under the influence of the drug... and he tries to kill the Nemesis doctor, Amis (HAROLD INNOCENT).   Brading dies, and it looks as though Tremayne will do so as well unless the drug can be identified. Craig, Sharron and Richard have only one clue to work on: that Tremayne had also lost his briefcase. Could both he and Brading have been trapped by being told that their cases had been found?   Who will be next? When Richard’s wallet disappears, it looks as though he has been selected as the next victim. He deliberately allows himself to be a bait but, although the others keep in telepathic contact with him, they are outwitted when he is abducted by two men posing as policemen. One is named Klein (PAUL EDDINGTON); the other is Barka (ERIC POHLMANN). Richard realises how it has all been done when he is taken to a phoney police station to reclaim his wallet.   It is another step in the Klein-Barka plot to turn Nemesis into a house of fear and suspicion, wondering where the next blow will come from and who will be the next victim, until the whole organisation is destroyed by its own agents.   Richard, too, finds himself programmed to kill, and his potential victim is... Craig. But what happens when an irresistible force meets an immovable object?     AN PRODUCTION   Series created by Monty Berman and Dennis Spooner   © Copyright Incorporated Television Co. Ltd. MCMLXVII     Stuart Damon   Alexandra Bastedo   William Gaunt   Anthony Nicholls     Craig Stirling   Sharron Macready   Richard Barrett   Tremayne     Eric Pohlmann   Paul Eddington   Harold Innocent   Richard Owens   Rachel Herbert   Conrad Monk   Bruce Boa     Barka   Klein   Doctor Amis   George Brading   Loretta Brading   Mechanic   American Colonel     Production supervisor   Director of photography   Art director   Editor     Geoffrey Haine   Frank Watts   Charles Bishop   Derek Hyde-Chambers     Musical director   Theme composed by   Post-production supervisor   Production manager   Casting   Stunt Arranger     Edwin Astley   Tony Hatch   Philip Aizlewood   Malcolm Chistopher   Anthony Arnell   Frank Maher     Sound editor   Sound recordists     Music editor   Associate art director   Set dresser   Construction manager     Roy Lafbery   Len Shilton Dave Bowen   Alan Willis   John Graysmark   Brian Rider   Bill Greene     Second unit director   Second unit cameraman   Camera operator   Assistant director   Continuity   Special effects     Ray Austin   Harry Gillam   Dudley Lovell   Ernie Morris   Sally Ball   Sid Pearson     Scenic artist   Production buyer   Make-up supervisor   Hairdressing   Wardrobe supervisor   Supervising electrician     A.J. Van Montagu   Sid Palmer   Gerry Fletcher   Michael Jones   Laura Nightingale   Ted Hallows       Made on location and at ASSOCIATED BRITISH ELSTREE STUDIOS ENGLAND.