Serial: YYY  Episode Nos. 370, 371, 372, 373, 374, and 375.  Title: The Monster of Peladon

50 years after his previous visit, the Doctor returns to the planet Peladon to find it once again in a state of crisis.  The Galactic Federation is at war with Galaxy 5, and the vital trisilicate supplies from Peladon are being interrupted by labor strife among the Pel miners, strife that is amplified when the spirit of Aggedor appears and strikes men down.  The Doctor suspects trickery is behind the apparitions, but his investigations are hindered when a Federation security force of Ice Warriors arrives...

starring Jon Pertwee as Doctor Who and Elisabeth Sladen as Sarah Jane Smith. Written by Brian Hayles, Produced by Barry Letts, and Directed by Lennie Mayne.

Originally transmitted from 23 March 1974 to 27 April 1974 on BBC1.