"Force of Life" is the ninth episode of the first series of Space: 1999. The screenplay was written by Johnny Byrne; the director was David Tomblin. The original title was "Force of Evil". The shooting script is dated 15 May 1974; the final shooting script is dated 24 May 1974. Live-action filming began Wednesday 29 May 1974 through Friday 7 June 1974. After a three-week hiatus, filming resumed Monday 1 July 1974 through Friday 5 July 1974; the hiatus was planned, as the Landaus' contract guaranteed them time off for a summer holiday.