Poirot and Hastings visit a movie set on the invitation of Hastings's friend, Bunny Saunders, the director of the movie. After an argument between the movie's producer, Reedburn, and his leading actor, Ralph Walton, Walton is sacked. Poirot then meets Prince Paul of Maurania, an old acquaintance who is watching his fiancée, the movie's leading actress, Valerie St Clair. Ralph Walton gets drunk and decides to go to Reedburn's house to confront him. On his way there he nearly crashes into Bunny Saunders's car. Valerie St Clair is seen leaving the house in a hurry, followed a few seconds later by a man. She runs to a neighbour's house in shock and asks them to call the police.
Poirot is woken up by a phone call in the middle of the night from Prince Paul, who wants him to help Valerie, but as discreetly as possible. The next morning, Inspector Japp tells Poirot his theory that perhaps a gypsy is responsible, as Reedburn objected to them living nearby. Poirot and Hastings go to speak to Valerie St Clair, who says Reedburn was blackmailing her, but she did not kill him. She will not say what the blackmail was about. Reedburn had asked her to call, but when she arrived, he was dead. She saw someone hiding behind the curtain, was terrified and ran out of the house. Poirot also speaks to Madame Oglander, the neighbour who called the police. She says that her family were playing bridge - but Poirot does not believe her, as he finds a card is missing from the table, suggesting the cards were put there to support the story.
Hastings discovers that Ralph Walton did not arrive at Reedburn's house at all - he had crashed his car before getting there. In Reedburn's desk, Poirot finds some newspaper clippings, showing Valerie St Clair is the daughter of Madame Oglander, who has very dubious origins - the matter of the blackmail. Poirot visits the Oglander household again. He tells Madame Oglander she was not playing cards at all the night before. She admits to him that the Oglanders have kept Valerie's secret, so that she can marry the Prince, and asks him to keep the secret, too. Poirot promises to say nothing. But later, Poirot explains to Hastings that Valerie St Clair and her brother had visited Reedburn on the night he died, hoping to change his mind about the blackmail. Reedburn refused, and in a moment of anger the brother punched Reedburn, who fell, hit his head, and died. So although there was no intent to kill, Valerie's brother committed an assault which led to death, and she is an accessory.
Poirot agonizes over what to do and decides he will not be pursuing the case any further. Japp has no more leads on the killer and closes the case, unsolved.