Doctor Who: The Invisible Enemy (1977)

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.

• Release Date: 1977-10-22
• Runtime: 1h 40min
• Director: Derrick Goodwin