The famous writer Ariadne Oliver invites the famous detective Hercule Poirot to a holiday at the Stubbs family estate, located in a small village near the camp site. The owner of the estate, George Stubbs, became a wealthy plebeian, and, according to Mrs. Oliver, a limited man, but in the dock business, lives on the estate with his wife, who is twenty years younger than him.

Recently, the architect Michael Weiman came to the estate to design and renovate something in the form of a temple called "Fad." The former mistress of the estate, Mrs. Folliat, lives in the gardener's house. This lonely woman, who lost two sons in the war, sold the Stubbs estate for debts. Mr. Alec Legg and his wife Sally, who live nearby, help arrange the celebration.

The guests of the holiday decide to entertain with the game "Find the victim", the script for which is to be written by Mrs. Oliver with the help of the famous detective. In a small boat house there will be a "corpse", at the prompts, players must guess who the killer is. The role of the "corpse" was initially intended by Sally Legge, but then she decided that she would be a fortune teller at the festival, and ceded this role to the local fourteen-year-old girl Marlene Tucker. For some reason, the writer fears that instead of a game, a real murder should happen.

Walking around the estate, Poirot meets with Michael Weiman, who wonders: why do we need to repair the “Fad”, built a year ago? The building does not harmonize with the house, and it was erected on a poor foundation.

The famous detective stops at the Stubbs house, where he gets acquainted with its inhabitants. Lady Hattie Stubbs, wearing wide-brimmed hats all the time, turns out to be a demented woman native to the West Indies. Her family owned the plantations, but during the earthquake, the estate burned down, and the girl's family died. Mrs. Folliat became her guardian, but Hattie was lucky - Mr. Stubbs fell in love with her and married her. According to others, her husband constantly spoils her, buys jewelry and expensive clothes. But the housekeeper, Miss Bruis, thinks she is on her mind. Lady Stubbs leaves early, citing a headache.

Poirot meets an old boatman, who says that the youngest son of the Follies, James, was a man who was not good and had a lot of debt. The boatman pronounces a strange phrase: "The follies will always live here."

At breakfast, Lady Stubbs, again wearing a wide-brimmed hat, receives a letter from her cousin Etienne Susie, who is due to arrive. The woman is afraid that she will not recognize the relative whom she saw as a girl. Lady Stubbs believes that Etienne is a bad person, capable of any dirty tricks. Referring to a headache, she goes to herself.

The estate is preparing for the holiday. Two female tourists violate the boundaries of the estate. Mr. Stubbs, seeing this through the window, yells at them, but his wife calls him inside the house. Poirot recognizes one of the girls - he met her yesterday when he was driving to the estate.

Marlene Tucker with interest looks at the famous writer and famous detective. She tells them that her grandfather saw the girl’s corpse in the forest, but the old man is considered to have survived from the mind, and no one listens to him.

Dressed in a wide-brimmed hat and hung with expensive jewelry, Lady Stubbs appears at the festival, where a lot of people gathered. Poirot passes from one attraction to another, meets tourist girls who are already leaving, and sees how Mr. Stubbs greets Etienne Susie who has arrived on a yacht.

Mrs. Oliver wants to visit Marlene: the girl is too frivolous if she has run away for the holiday. Together with Poirot they go into the house and see a strangled girl lying on the floor. The writer's forebodings came true.

A police inspector arriving at the scene interrogates witnesses. There were about two hundred people at the festival, everyone could go into the house and commit a crime. Who could interfere with Marlene, a stupid talker, the daughter of a cook, who had only guys and movie stars on her mind? As soon as the money appears, she immediately runs to buy lipstick and perfume, although her parents thought that it was too early for her to use makeup. Mrs. Oliver thinks that Marlene might know someone else's secret, but the inspector considers it stupid.

The famous detective Hercule Poirot comes to the aid of a police inspector. Etienne Susie, who was so afraid of Lady Stubbs, attracted their attention. She disappeared somewhere, and her husband is concerned about her absence.

Etienne is surprised by the reaction of Lady Stubbs to his letter: a few weeks ago he wrote that he was coming, and later specified the date of arrival. Why was she so scared this morning?

Police are looking for the missing lady Stubbs. She did not go out through the gate, climb over the fence, as tourists do, she could not either, as she was wearing a long skirt and high-heeled shoes. Miss Bruis believes that Lady Stubbs is walking somewhere, and her husband has too much imagination. Not such a fool lady, as everyone believes.

Mr. Stubbs claims that his wife did not receive a letter from her cousin. He says Lady Stubbs is scared of him, as she says she kills people.

The inspector narrows the circle of suspects. Only one who had the key could get into the locked house, or Marlene herself opened the door, but she could only open the organizers of the game. Lady Stubbs asked Miss Bruis to take the girl food at a quarter past four, and at five o’clock she was found dead.

The inspector interrogates those whom Marlene could let in. Michael does not know anything about the incident, but is surprised that Lady Stubbs could show concern. He also does not consider her moronic.

Sally Legg was always in her fortune-telling tent and went out only to the tea tent for a bite.

Immediately ten years old, Mrs. Folliat cries all the time and worries about Hetty. The woman believes that her pupil fled, not wanting to meet with her cousin. Poirot seems that Hetty is dead, and Mrs. Folliat knows this and does not agree much.

Poirot sympathizes with Mr. Stubbs, who cannot find his place. Since he was on the lawn all day, the famous detective does not suspect him.

Miss Bruis complains to Poirot that Lady Stubbs has enslaved her husband. She is cunning, deceitful, pulls money from him for outfits and jewelry. Now she is alive, healthy and has run away with some kind of fan. In the evening, yawning, went to her room and immediately went out through the side door.

Thinking, Poirot comes to the “Fad”, finds there a keychain from Sally Legg's bracelet and meets an unfamiliar young man who is looking for a way out of the estate. Sally comes into the building to find a keychain. The famous detective decides that yesterday she didn’t come to the tea tent, but to “Fad” to meet someone. Sally complains that she is unhappy in marriage. Some strange people called her husband, but he didn’t tell her anything. At first she thought that he had a mistress, but then she realized: the thing is different. Alec Legg appears in the building, who is afraid of someone.

Lady Stubbs' hat is found in the river. Police raids Etienne's yacht, but finds nothing.

Poirot examines the tent of a fortuneteller. Through the wall opposite the entrance you can go out and go unnoticed through the thicket to get to a small gazebo, which the famous detective also examines.

The police investigation is at an impasse; Lady Stubbs' bodies were never found. The news comes that the old boatman drowned - after drinking more than he should, the ninety-two-year-old man fell into the river.

The inspector seeks help from Hercule Poirot. The famous detective visits the Marlene family. He learns that the deceased boatman is the grandfather of the murdered girl, he once worked on an estate owned by the Folliat family.Recently, the old man got money, and he was often seen drunk, and Marlene bought herself cosmetics with the money someone gave her.

Poirot comes to Alec Legg. Sally left, and the famous detective advises him to go after his wife. Alec is a member of a political party, with a member of whom he had an appointment in Fad. When Alec decided to deviate from the rules of the party, they began to threaten him. On the advice of Poirot, Alec decides to make peace with his wife.

Poirot meets with the police inspector - he knows who the killer is and where Lady Stubbs' body is hidden. Mr. George Stubbs killed his wife.

Poirot comes to Mrs. Folliat. Her youngest son, James, was not killed in the war; he defected. Mrs. Folliat was under the care of a demented girl with a huge fortune. James Folliat married her, with the help of ingenious combinations under a new name, George Stubbs took the status of his wife and became the owner of his own estate. But he was recognized by an old boatman who dropped the phrase: "The follicles will always live here." James Folliat could not marry, since he was already married to a woman associated with the criminal world.

James Folliat came to the estate with his legal wife, who portrayed a moron. They were prevented by the arrival of Etienne, who would immediately have guessed that he was not facing his cousin. Also, the old boatman was chatting a lot with his granddaughter. Giving the girl money for silence, James and his wife came up with a plan. By setting a feast for Etienne's arrival day and thinking that he is killing people, James's wife plays two roles: a dumb lady Stubbs and a tourist. She hides her face under a wide-brimmed hat, and the tourist's clothes - under a long skirt. As a tourist, she spends the night at the camp site, so Miss Bruis saw her coming out through the side door.

Having asked Miss Bruis to take Marlene food so that she appears in the house at a certain time, James's wife comes into the fortress’s tent, goes out through the back wall and, unnoticed by anyone, sneaks into the arbor where the tourist’s backpack was hidden. Having changed clothes, she comes to the boat house, strangles Marlene and leaves the camp site. At the moment, the police are busy looking for her.

The real Hattie was killed and the body was hidden under the "Fad", which is now breaking.