Episode 5, "At Night All Cats Are Gray," is perhaps the most famous, due to the welcome and unexpected presence of Sir Christopher Lee, a future Monster in 1957's "The Curse of Frankenstein," playing opposite the screen's original 1931 Monster, Boris Karloff. Colonel March is dining in Piccadilly Circus with Inspector Ames (Ewan Roberts) when a mysterious woman (Isabel George) interrupts, hoping the Colonel will pretend to be her lover because she is being followed by a strange man and fears for her life. He instantly recognizes the girl as a French model named Fleur, working in London for the Jean-Pierre Couturier. Later that night, March is attacked by the stranger (Peter Dyneley), who demands certain clothing designs that Fleur supposedly slipped the Colonel. In the morning, Fleur is found lying dead on the floor of her apartment, wearing a different pair of shoes than she had earlier, as the investigation continues with Monsieur Jean-Pierre (Lee) and his wife (Frances Rowe) prime suspects. The Colonel solves this case by revealing a color-blind murderer, and how all cats are gray at night. Completed by December 1953, the 31 year old Christopher Lee towers over the other actors, affecting a French accent, and receiving top billing among the guest cast of five players. He would go on to co-star with Karloff, his actual London neighbor from 1964 to 1968, in 1958's "Corridors of Blood" and 1968's "The Crimson Cult."