The Reverend Leonard Clement, vicar of St Mary Mead, narrates the story. He lives with his much younger wife, Griselda, and his nephew, Dennis. Colonel Lucius Protheroe, Clement's
churchwarden, is a wealthy, abrasive man who is widely disliked. Clement encounters Protheroe's young wife, Anne, embracing Lawrence Redding, a visiting artist. While promising that he will not reveal their affair, he advises Redding to leave the village at once. The next day Clement is scheduled to meet Protheroe to go over irregularities in the church accounts. Clement is called away to visit a dying parishioner, but learns on arrival that nobody had asked for him. Upon returning home, Clement encounters a distressed Redding at the vicarage gate, then discovers Colonel Protheroe dead at his writing desk with a gunshot wound to the head. He summons Dr Haydock. The police, led by Colonel Melchett and Inspector Slack, are confounded by several details, including a note left by Protheroe that conflicts with Haydock's opinion of the time of death, and the claim of some witnesses to have heard a shot in the woods. Both Lawrence Redding and Anne Protheroe confess to the murder. However both are exonerated – Redding because he insists on an inaccurate time of death and Anne because Miss Marple had clearly seen she was not carrying a pistol. Other suspects include Archer, a man treated harshly by Protheroe for
poaching; Mrs Lestrange, a mysterious woman who has appeared in the village recently; Dr Stone, an archaeologist excavating a
barrow on Protheroe's land; and Stone's assistant, Miss Cram. Miss Marple sees Miss Cram carrying a suitcase into the woods at midnight; Clement later finds it, along with a crystal of
picric acid. The suitcase contains valuable silver belonging to the Protheroes; Dr Stone turns out to be an impostor who has replaced the Protheroes' belongings with replicas. Mrs Price-Ridley receives a threatening phone call. Anne Protheroe discovers a portrait slashed to pieces with a knife. A police handwriting expert examines the victim's note and determines that Protheroe did not write it. After Clement is inspired to give a far more vigorous sermon than usual, he receives a call from Hawes, his sickly
curate, who says he has something to confess. Clement arrives at Hawes' rooms to find that he has taken an overdose. He discovers the real note Protheroe was writing when he was killed, which reveals that Hawes was responsible for stealing money from the church. Miss Marple explains that the killers are Lawrence Redding and Anne Protheroe. In love with Anne, Redding decided they could be together only if he eliminated her husband. On the pretext of seeking advice from Clement, he left his pistol in a potted-plant holder at the vicarage. He then planted the picric acid in the woods nearby, rigging it to explode and create a second gunshot sound that would confuse witnesses. In the evening Redding made the false call to Clement to get him out of the house, while Anne walked past Miss Marple's home without a handbag and in a close-fitting dress to show she was not carrying a gun. She retrieved the pistol, killed her husband, and left the vicarage. Redding entered, stole the note that incriminated Hawes, and planted his own note falsifying the time of death. Both conspirators had confessed to the crime, but with obvious falsehoods in their stories, each appearing to exonerate the other. Redding drugged Hawes and planted Protheroe's note to make it look as though Hawes had tried to kill himself. Dr Haydock saves Hawes' life. Miss Marple proposes a trap that tricks Redding into incriminating himself; he and Anne are arrested. The ending ties up the loose ends. Lettice reveals that Mrs Lestrange is her mother, Colonel Protheroe's first wife, who is terminally ill; Lettice destroyed the portrait of the first Mrs Protheroe so that the police would not recognise and suspect Mrs Lestrange. Lettice and her mother depart to spend the latter's last days travelling. Miss Cram knew nothing about the false Dr Stone's plot, and Griselda and Dennis confess to having threatened Mrs Price-Ridley as a practical joke. Griselda tells her husband that she is pregnant. ==Principal characters==