It is a quite unusual detective story where each character has a motive to commit a crime. The scene is laid in a fictional English village. The novel is narrated in the third person. Dr James Sheppard becomes an assistant of Hercule Poirot. This is he, who tells the story to the reader. Mrs Ferrars, a rich widow, died. The reason was the drugs overdose. The peasants believe it was a suicide. They say Mrs Ferrars killed her husband by poisoning many years ago. But then another widower died. He wanted to marry Mrs Ferrars. People started suspecting his sister-in-law because she had many debts. Her daughter Flora, major Blunt and many relatives of the late bridegroom are suspected. The bride of the prime suspect asks Poirot to investigate this difficult case and find the killer.