Available on Pluto TV, Prime Video, BritBox, Tubi
S12, E10: Transported back to the Earth of the distant future from the Ark, the Doctor, Harry, and Sarah discover that they have unwelcome company. An alien warrior is conducting deadly experiments to assess the suitability of the human race as an adversary prior to a full scale invasion of Earth.
Sci-Fi · Mar 1, 1975 · 25 min