Charles Gray does not appear in this story. The role of "Markheim" is taken by series regular Charles Drake, who is first seen awaking from a dream, which he describes to his friend Carla. The dream he tells her, is actually the plot of one of his favorite short stories, "Markheim" by Robert Louis Stevenson, but he was himself Markheim in the dream, and she Markheim's girl-friend. The dream is then enacted as the substance of the episode.