Doctor Who (1963): The Doctor has entered the computation Matrix to prove his innocence. But his opponent is prepared for him and the two engage in a mental duel to the death.
Elisabeth Sladen, Frazer Hines, Jacqueline Hill, John Levene, John Scott Martin, Jon Pertwee, Katy Manning, Nicholas Courtney, Pat Gorman, Patrick Troughton, Peter Davison, Tom Baker, William Hartnell, William Russell
Adventure, Drama, Sci-Fi
Maybe also available here.