Poirot is invited by Sir Henry Angkatell for a country weekend at The Hollow, giving Poirot a chance to observe the strange Angkatell family and their relationships to each other. John Christow, a handsome and charismatic doctor, is there with his plain and docile wife, Gerda. But is there a relationship going on between John and Henrietta, a vibrant young artist and member of the Angkatell clan? The charming but slightly batty Lady Angkatell is doing her best to set up Henrietta with Edward Angkatell, to ensure a long line of Angkatells at the family estate. But in comparison to John Christow, Edward appears pale and insignificant and Henrietta, although fond of Edward since childhood, can only repeatedly turn down his marriage proposals. Midge watches on sadly. She has been in love with Edward for as long as he has been in love with Henrietta. Dramatically, that evening, the garden doors open and the famous actress, Veronica Cray descends on the party with the pretence of needing matches. She spots John with surprise and greets him. They had at one time been engaged. She demands John escort her home so they can catch up on old times. John bashfully obliges and it does not take long before they are making love in the swimming pool pavilion. The next day, Poirot, having noticed the family's love of games, is annoyed to find a murder tableau arranged around the swimming pool. Gerda stands over John's bleeding body holding a gun while the rest of the family appears from different paths leading to the pool. Poirot suddenly realises that it is actually real and the blood that seeps into the pool really comes from John's stomach. John moans Henrietta's name and dies. Poirot springs into action but not before Henrietta grabs the gun from Gerda and accidentally drops it into the pool. The police arrive and begin their enquiries. It seems obvious that Gerda did it, but she claims that she did not. Could it all be a set up? Sir Henry asks Poirot to do his own investigating. It seems everyone has his or her own motives for killing John. Even Veronica had had a blazing row with him that morning, when he refused to run away with her. But nothing seems to add up. Henrietta admits to having an affair with John and Poirot has evidence that she had been in the pavilion on the fateful morning. Lady Angkatell had been wandering around with a loaded gun in her basket of eggs. Then the gun which Gerda was holding turns out not to be the gun which the fatal shot was fired from. So where is the actual gun? Poirot begins to feel that someone is playing games with him. After a chance remark by the inspector, Poirot realises where the real gun must be and pieces together that the entire family must be protecting someone. Poirot, Henrietta and Lady Angkatell all realise at the same time that there is a vital piece of evidence missing... the gun holster. Henrietta rushes off in her car and manages to lose the police. But Poirot is one step ahead and guesses where she will be going. He arrives at Gerda's house a little after Henrietta. Gerda explains how and why she killed the husband that she adored.... Unable to sleep she had wandered down to the pavilion and seen John making love to Veronica and felt her whole world crashing around her. John was not the person that she thought he was. She knew from her detective novel that it was easy for the police to identify which bullet was shot from which gun and so shot him with one, hid it in a bush and then held the other. Ironically, John loved Gerda more than any of the other women in his life and it was his dying request that Henrietta should protect Gerda, his murderer. So Henrietta took over from then on, hiding the gun in one of her sculptures and encouraging the family to lead the police and Poirot 'down the garden path'. Poirot, angry at being deceived, makes sure that Gerda is punished but forgives Henrietta, recognising her ingenuity and her love for John.