An approaching Alien spaceship is detected on monitoring equipment at UNIT HQ, where the Brigadier is entertaining two visitors - Chinn, a civil servant making a security inspection, and Bill Filer, an American agent sent to discuss the threat of the Master. The Ship lands in England and the UNIT team, joined by Hardiman and Winser from the nearby Nuton power station, meet its occupants: beautiful golden-skinned humanoids called Axons.

Originally transmitted 13/03/71 - 03/04/71
Producer: Barry Letts
Directed by: Michael Furguson