Doctor Who: The Invisible Enemy (7.2)

Movie · 1977 · 1 h 40 min · Science Fiction, Drama, Adventure

A three-man rocket crew are nearly done with their mission to Titan Base until a course change puts the rocket in the path of a strange cloud in space. By the time they arrive, they have come under the control of a sentient virus which threatens the galaxy. When the TARDIS picks up an emergency message, it flies into the cloud, infecting the Doctor. To save himself and others, he must undertake a dangerous journey.

Directed by: Derrick Goodwin

Starring Tom Baker, Louise Jameson, John Leeson, Michael Sheard, Brian Grellis, Jay Neill, Edmund Pegge, Frederick Jaeger

We don't know where to watch it in the US.