City of Death: Part Four 1979
9.1 422 Scaroth, the last of the Jagaroth, forces Romana to build a field interface stabilizer for his time machine. Romana reluctantly does so, not knowing that the full extent her action will lead to the total non-existence of all life on Earth. Humans will never have existed.
Runtime: 25
Starts: Tom Baker, Lalla Ward, Julian Glover, Catherine Schell
Director: Michael Hayes