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.

• DirectorDerrick Goodwin
• Release22 October 1977
• Genre
  Science Fiction / Drama
• Duration1h 40m
• Budget?
• Revenue?
• Rate
  

  7.2
  4 reviews
• Productions

  BBC