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