Theft which has a similar plot. There were changes to the character names and story details (e.g., the plans are for a new state-of-the-art bomber rather than for a new submarine). "The Third Floor Flat" Four young people, two women and two men, are returning after a night out to the home of one of the women – Patricia Garnett. She is annoyed as she cannot find the key to her flat on the fourth floor of her apartment block in her handbag. The porter does not have a spare key, nor is there a fire escape, but the suggestion is made that the two men, Donovan Bailey and Jimmy Faulkener, make their way up through the coal lift and let the women in. They go to the basement and make their way up. Exiting the lift, they find the kitchen in darkness and Donovan instructs Jimmy to remain where he is while he locates the light switch. He does so but the light fails to work and Donovan makes his way to the sitting room where he switches on that room's light; they suddenly realise that they have miscounted the floors and that they are in the flat below which, according to a pile of letters, seems to belong to a Mrs Ernestine Grant. They make their way up to the next floor again via the coal lift and let Pat and the second lady, Mildred Hope, into the former's flat. They notice that Donovan has cut himself as there is blood on his hand. He washes it off but cannot find a cut to explain the blood and voices his fears to Jimmy. Again using the coal lift, they return to Mrs Grant's flat below and soon spot a foot sticking out from under a curtain – it is the dead body of Mrs Grant. Back on the landing with the girls, they are discussing calling the police when a voice interrupts them, agreeing with their plan of action. It is the occupant of the fifth floor flat Hercule Poirot, the famous detective. Going into Mrs Grant's flat, Poirot finds it curious that the light switch in the kitchen now works. He also sees that the red tablecloth disguises a patch of blood, which Donovan touched to get the blood on his hand. The body was moved after death. The police arrive and Poirot and the four people