The Stones of Blood: Part Four 1978
7.7 254 Aboard a hyperspace prison ship, two justice machines called the Megara, known for swift verdicts and harsh punishments, arrest the Doctor for breaking an infraction, with trial and execution to be carried out immediately.
Runtime: 23
Starts: Tom Baker, Mary Tamm, Beatrix Lehmann, Susan Engel
Director: Darrol Blake