England, early thirties. Hercule Poirot with his old friend and assistant captain Hastings come to the seaside resort of Saint-Loup in the south of England. Near the hotel “Majestic”, in which they stopped, they meet a young girl. Nick Buckley. In conversation for a cocktail it turns out that she is the owner of the house standing on the edge, Endhouse. Nick Buckley, by the way, says that he has avoided death three times in the past three days. It can not but interest Poirot. In addition, in a simple felt hat, Nick, forgotten at the table of random acquaintances, turns out to be a round hole with even edges – an obvious trace of a bullet. Poirot attributes the hat to a girl who dines with friends. Poirot negotiates with Nick about his visit to Endhouse.
In the evening at the hotel, while dancing, Poirot tells Frederic that Nick was shot. Freddie, who believed that her friend was inventing all her accidents, was shocked. Poirot and Hastings meet Croft and, at his request, go into the wing to get acquainted with his wife, confined to bed after the railway accident. Crofts are unusually welcoming and too intrusively emphasize their “Australianism”.
Nick goes to the hotel to Poirot to show a telegram about the arrival of Cousin Maggie. She looks alive, but dark under her eyes. It can be seen that her anxiety is consumed and, as Poirot suggests, not only because of the attempts made on her. Nick invites Poirot and Hastings in the evening at Endhouse to watch fireworks.
At Endhouse, guests are gathered: Freddie, Lazarus, Poirot and Hastings. Here came the cousin Nick, Maggie, – in an old black evening dress, without makeup. She genuinely wondered who needed to encroach on the life of Nick. Appears herself a mistress – in a black dress just received from a tailor, with an amazing bright red Chinese shawl thrown over her shoulders. Behind the cocktails, it comes to Michael Seton, a brave pilot who alone performed a round-the-world flight on an amphibian “Albatross” and disappeared a few days ago. Hope that he is alive, almost no more. It turns out that Nick and Freddie were familiar with it. Nick leaves to talk on the phone and is long absent. Appearing again, she calls everyone to watch the fireworks. The spectacle is magnificent, but the piercing wind blows from the sea, Poirot, afraid of catching cold, decides to return to the house. Hastings follows him. Not far from the house they see a body stretched out on the ground in a bright red shawl. Poirot blames himself for this death. Nick appears in the doorway and cheers cousin gaily. Poirot turns the body over – the victim is Maggie Buckley. She died instead of Nick – that, having gone behind the jacket to the house, left her his shawl. Nick is shocked. She is put in a private hospital. To protect Nick from possible attacks, doctors at the request of Poirot forbid visits with her.
Poirot analyzes the situation. He writes a list of all “actors” and considers the motives and suspicious circumstances associated with each of them. Hastings falls asleep in fatigue in the armchair, and the last thing he sees is Poirot, throwing crumpled sheets with his calculations into the wastebasket. When Hastings wakes up, Poirot sits in the same place, but his eyes are cast like a cat’s gleam, familiar to Hastings, – this is a sure sign that Poirot guessed something important. And in fact, the detective has unraveled the mystery of Nick, a visit to the clinic confirms his conjecture. Nick was engaged to the deceased pilot, Michael Seton. The engagement was kept secret because of Uncle Michael, the old Sir Matthew, a rich man, an eccentric and a misogynist. Michael’s successful flight would force Sir Matthew to fulfill any desire of his nephew, including agreeing to marry. But fate decreed otherwise: already during the flight of Michael his uncle had an operation, and he soon died. Before leaving, Poirot asks Nick for permission to look for her will, and she easily allows him to “inspect anything.”
In Endhouse, Poirot converses with the maid Ellen, who mentions the existence of a hiding place in the house, and also reports that before the tragedy, she was overcome by misgivings. From the finding of the detective letter Freddie Rais it becomes clear that she uses drugs. She “from beginners”, makes the diagnosis of Poirot. In the chest of drawers among the underwear, the detective finds and begins to read Michael’s letters. Hastings is shocked. “I’m looking for a murderer,” Poirot reminds him sternly. The letters here are clearly not all. From the farewell letter before the beginning of the flight, it becomes clear that Michael, without bothering with formalities, wrote a will on the piece of paper, leaving all his property to the bride. Poirot and Hastings return to the hospital. Nick denies the existence of a hiding place. But she suddenly remembers that Croft, who had told her to make a will, he volunteered to put the letter down. So Charles must have a will. But he is not in the lawyer’s office.
Kroft swears that he omitted the letter, and his wife shows a touching concern about Nick. But this does not stop Poirot tearing off a scrap of newspaper, which left a fat trace of Croft’s thumb and index finger to send to the police. The sleuth thinks that “the good man Monsieur Croft is something too good”. Her parents come to pick up the body. They are charming, simple-minded old people, dejected with grief and full of sympathy for Nick.
From a conversation with a lawyer of the Seton family, Mr. Whitfield, Poirot, it becomes clear that Nick must receive a huge sum. Poirot and Hastings return to St. Louis. Calling the hospital, the detective learns that Nick is dangerously ill. She has cocaine poisoning. She ate a chocolate candy, to which he was mixed. Nick violated the prohibition of Poirot not to touch the sent food, because to the box was attached a card “With greetings from Hercule Poirot.” Cocaine in sweets puts under suspicion Frederick Rais. In addition, in the lost will, she was declared the heir, and at the moment Nick has something to leave behind.
Poirot decides to announce the death of Nick. Friends Nick, shocked, buy flowers and wreaths for funerals, and Hastings dumps a fever attack. Mother Maggie sends Poirot a letter to her daughter, written by her immediately upon her arrival at Endhouse. But one phrase in this letter makes Poirot take a fresh look at the matter – and unravel it. The next day, Poirot collects all the participants of the drama at Endhouse. Among them are Charles Wise and Croft. Charles Wise announces to the assembled that this morning he received his cousin’s will and has no reason to doubt its authenticity. According to the will, everything that Nick owns remains to Mildred Croft as a token of gratitude for the invaluable services that she rendered to Philip Buckley, father of Nick, who once lived in Australia.
Unexpectedly, Poirot proposes to arrange a seance. Extinguish the lamps. Suddenly, before the eyes of those present, a vague figure appears, floating like air. All in shock. The light is lit – in the middle of the room there is a living Nick under a white veil. A police inspector, Jepp, appears, arresting Croftov, a large number of forgeries specialists. At that moment someone shoots at Frederic, wounded her in the shoulder, and gets a bullet of a policeman himself. This is her husband, a cocaine, who lost his human form. But he did not kill Maggie. On duty at Endhouse from the beginning of the evening, Jepp saw a certain young lady take a revolver out of a secret niche, wipe a handkerchief and, going into the hallway, put it in Mrs. Rice’s cape… “Lies!” shouted Nick.
Poirot claims that Nick killed Maggie to inherit the money of Michael Seton. She was also called Magdalena Buckley, and it was with her that the deceased pilot was engaged. Policemen are already waiting for Nick in the hallway with an arrest warrant. Nick behaves arrogantly, not condescending to deny his guilt, but before going to ask Fredericks for an hour – as a memory, she says. The watch served to transport and store cocaine. “For her, this is the best way out,” says Poirot, “it’s better than the hangman’s rope.”