Exiled to Earth in the late 20th century by his own people - the Time Lords - the newly regenerated Doctor arrives in Oxley Woods alongside a shower of mysterious meteorites. Investigating these unusual occurances is the newly-formed United Nations Intelligance Task Force - UNIT for short. Lead by Brigadier Alistair Gordon Lethbridge Stewart, UNIT are soon called into action when people and meteorites start going missing. Most puzzling of all is the attempted kidnap of a strange hospital patient - a man with two hearts, who insists he recognises the Brigadier... The new Doctor soon joins forces with his old friend, UNIT, and recently recruited Dr Liz Shaw, but time is running out... Irregular things are happening at a nearby plastics facotry, while faceless creatures lurk in the woods. The nestenes have arrived, and want to conquer the Earth...

This story originally broadcast: 3rd-24th January 1970.

Producer: Derrick Sherwin
Directed by: Derek Martinus