The Square Triangle

Summary
Liz Newton and her lover Cass are planning the murder of Liz's husband Jack. A UFO craft lands near to her remote woodland cottage and an alien gets out to explore the surroundings. Believing the alien to be Jack, Liz and Cass shoot and kill it. Straker arrives in search of the alien and takes the couple away for questioning.

=Episode Cast=
 * Adrienne Corri - Liz Newton
 * Dolores Mantez - Nina Barry
 * Gabrielle Drake - Lt. Gay Ellis
 * Antonia Ellis - Joan Harrington
 * Gary Myers - Skydiver Capt. Lew Waterman
 * Ed Bishop - Cmdr. Ed Straker
 * Keith Alexander - Lt. Keith Ford
 * Michael Billington - Col. Paul Foster
 * Patrick Mower - Cass Fowler
 * Ayshea Brough - SHADO Operative (as Ayshea)
 * George Sewell - Col. Alec Freeman
 * Hugo Panczak - SHADO Mobile Navigator
 * Godfrey James - Game Warden Mitchell
 * Anthony Chinn - Alien
 * Allan Cuthbertson - Jack Newton
 * Norma Ronald - Miss Ealand
 * Mel Oxley - Space Intruder Detector SID (voice) (uncredited)
 * Robert Rietty - Keith Ford (voice) (uncredited)

=References=