A bomb hits nearby where the Jefferson's are dining and two of them are killed, and Conway Jefferson loses his legs.
Seven years later, the body of a young blond is discovered in the Bantry's library at Gossington Hall by the maid. Dolly Bantry calls Miss Marple over to see it. Colonel Melchett, the chief constable, arrives and takes charge of the investigation. He is pointed in the direction of Basil Blake, who had been seen around the village with a young blond girl.
Melchett goes to see Basil Blake, but his girlfriend arrives while he's there, and Blake tells him that he'll have to look elsewhere for 'Bantry's blond'.
Melchett gets a call from Superintendent Harper, who tells him about the disappearance of a young blond, Ruby Keene, at the Majestic Hotel. They ask her cousin, Josie Turner, to identify the body and she confirms that it is Ruby Keene.
She tells them that the previous night, Ruby had been dancing with Raymond Starr, and then with George Bartlett - and that was the last they had seen of her. She had supposed to have been doing another dance with Raymond Starr, but Josie had had to do it, even though she had had a swollen ankle. That morning, Conway Jefferson ahd insisted that they call the police to alert them about her disappearance.
Melchett and Harper take her to Gossington Hall to meet Colonel Bantry, where they watch closely to see if they recognise eachother. When Josie tells the Bantrys and Miss Marple that Ruby was reported missing by Conway Jefferson, Dolly Bantry realises that they know the Jeffersons, and it seems a bit to much of a coincidence that Ruby's body was found in their library.
Miss Marple and Dolly Bantry decide to go to the Majestic Hotel to do a bit of sleuthing. They go to see Conway Jefferson, who is very surprised that Ruby was found in the Bantrys' library. Conway Jefferson explains that he altered his will so that Ruby Keene would inherit £50,000 and he also tells them that he planned to adopt her. This gives Mark Gaskell and Adelaide Jefferson both motives to kill Ruby, who have been dependant on their father-in-law since the death of his children (their wife and husband).
Melchett and Harper also turn up at the Majestic, and interview George Bartlett, who danced with her before she said she had a headache and went up to her room. He had then walked around for a bit. Then Harper interviewed Raymond Starr, who told him exactly what Josie had, that he was supposed to dance with Ruby again, but had to dance with Josie instead. They bumped into George Bartlett, who told them that his car had gone missing.
Dolly Bantry talks to Adelaide Jefferson, who tells her that she is in love with Mark Gaskell, when Dolly believes that it is Raymond Starr. Meanwhile, Miss Marple was talking to Mark Gaskell, who tells her that he is in love with Josie Turner. They both say that they were playing bridge with Conway Jefferson and Josie until after Ruby died, and when Josie went off to dance with Raymond, Adelaide went to write some letters.
George Bartlett's car is soon found burnt out, with a body inside, which is believed to be that of Pamela Reeves, a young girl scout who went missing on the night before after supposedly going to Woolworths.
Harper asks Miss Marple to sit in on him interviewing the other girl scouts, and she tells him to call Florence back in. Miss Marple tells her that with-holding information from the police is just as bad as purgory and it is better to tell the truth. Florence tells her that Pamela was approached by a film producer, who told her that she would have a chance. On the previous night, she had gone off to have some pictures done and had never come back.
Miss Marple goes back to St. Mary Mead and visits Basil Blake's girlfriend Dinah Lee. She tells her that she should start using her married name to show the village that they are respectable people, because they are going to need all the support they can get now, because Basil will soon be arrested for murder. Basil Blake arrives home and explains that after having an argument with Dinah, he had driven home drunk and had found the body on his hearth rug. He thought he would be implicated and decided that he would take the body to Gossington Hall and leave it in Bantry's library.
Miss Marple and Dolly Bantry then go to the police and Miss Marple explains what had happened. She tells Melchett and Harper that the body in the library wasn't Ruby Keene, but Pamela Reeves. Josie and Adelaide had looked for anyone that would fit Ruby, and they spotted Pamela and told her that she could have a film shoot.
On the night, they drugged Pamela and, while Ruby was still alive dancing, Adelaide took her to Basil Blake's house and laid her on the hearth rug and strangled her. Meanwhile, Josie had put a drug in Ruby's coffee and Ruby then went up to her room to get changed and went to wait for Josie in Josie's room. When Raymond Starr came to the table to ask Josie where Ruby was, they went up to her room, where they found nothing. Josie then went to her room to change, she she administered an injection to the unconsious Ruby and killed her. She later took her to the quarry in the car and set it alight.
Miss Marple suggested that they would probably try to kill Conway Jefferson, so they decided to set a trap. That night, Josie creeps into Conway Jefferson's room and is caught by police. Her and Adelaide are taken into custody for the murders of Ruby Keene and Pamela Reeves.