The last episode from the first season of this long-running BBC series. While trying to return to 1960s London the Doctor (the first incarnation played by William Hartnell), Ian (William Russell), Barbara (Jacqueline Hill) and Susan (Carol Ann Ford) discover themselves in eighteenth century France caught up in the revolution. They are arrested as traitors and Barbara and Susan are sentenced to death. The Doctor takes on the disguise of a leading revolutionary and must outwit his enemies to become reunited with his companions and save Barbara and Susan.