Margot Wendice: The charming, naïve, and wealthy wife of Tony, Margot has no idea that Tony knows of her past affair with Max, nor does she suspect that Tony is planning to murder her.
Max Halliday: An American murder mystery writer, Tony had an affair with Margot during the time Tony was playing professional tennis tournaments in America. He is still in love with Margot and comes to visit the couple in London.
Tony Wendice: Margot’s husband, Tony is a former professional tennis player who married Margot for her money. He is selfish and arrogant and has an elaborate scheme to murder Margot because of jealousy over a past affair between Margot and Max.
Captain Lesgate: An old schoolmate of Tony’s and a convicted criminal, Lesgate is now being blackmailed by Tony into murdering Margot. He seems willing to do anything for money.
Inspector Hubbard: A British Inspector of Police, Hubbard is a bit eccentric, but thoughtful and thorough.
Thompson: A police officer.