Science FictionDramaAdventure

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.

Credits

Tom BakerThe Doctor

Louise JamesonLeela

John LeesonK-9 Mk. I (voice) / Nucleus (voice)

Michael SheardLowe

Brian GrellisSafran