The Doctor's friends are captured by soldiers in post-Revolutionary France, during the reign of terror in which anyone suspected of Royalist sympathies is immediately executed. Ian is thrown into jail with a dying English prisoner, who gives him a vi... (more)tal message for English master spy James Stirling. Robespierre's right-hand man, Citizen Lemaitre, secretly helps Ian to escape. The Doctor arrives, disguised as a prominent Citizen to arrange for his friends' release, but Lemaitre sees through his guise and threatens to have Susan executed unless the Doctor leads him to the escape route run by Jules Renan. There, Lemaitre reveals himself to be Stirling, and enlists Ian and Barbara's help to complete his mission. So doing, they see Paul Barrass inviting Napoleon Bonaparte to rule the country as part of a triumverate after Robespierre is overthrown. Stirling tries to stop this for the sake of his own country, but he is too late to prevent the mob from turning on Robespierre. Nevertheless he is true to his word and releases Susan, allowing the travellers to escape from Paris.

Donald Morley, Edward Brayshaw, Jack Cunningham, James Cairncross, Keith Anderson, Terry Bale