The Square Triangle

[3] Straker allows a UFO to land in Southern England in an attempt to capture the craft, and its alien crew, by sending out a fleet of SHADO mobiles.

Foster and his investigation team arrive with the dog to find the dead alien, from which the conniving pair are taken to SHADO headquarters, where they are debriefed of the events, and eventually given an amnesia drug to make them forget everything that had occurred within the previous twelve hours.

[1] The closing graveyard scene was shot outside the Church of St Mary the Virgin in Harefield, London Borough of Hillingdon.

[7] Describing it as "one of the most brilliant and successful" instalments, John Kenneth Muir praises the episode for its themes of sacrifice and "hypocrisy" in war ("Here, an innocent man must be allowed to die for the secrecy of [SHADO's] cause.")

Muir also comments on the cinematography of the graveyard scene, noting that the camera zooms out to indicate "a kind of withdrawal, in shame and horror, at what has occurred".