First broadcast 30th December 1977.<br /><br />Charles Nesbitt, an expert on chemical warfare, has a plan to contaminate the water supply of London with lethal hallucinogenic drugs.<br /><br />Gordon Jackson - George Cowley<br />Martin Shaw - Doyle<br />Lewis Collins - Bodie<br />Keith Barron - Charles Nesbitt<br />Donald Douglas - Eric Sutton<br />Di Trevis - Susan Fenton<br />Angus MacKay - Gerald Harvey<br />Trevor Adams - Benny<br />Christopher Ellison - Biggs, CI5 Agent<br />Peter Penry-Jones - Cummings<br />Penny Irving - Pam<br />Gloria Maley - Pretty Nurse (as Gloria Walker)<br />Bridget Brice - Betty, Cowley's Secretary<br />Donald MacIver - Hoskins<br />Melanie Peck - Barmaid<br />Ian Fairbairn - Ted Miller<br />Malou Cartwright - Ted Miller's Secretary<br />Pola Churchill - Girl<br />Maxwell Craig - Man in Pub<br />Guy Standeven - Doctor
