A Pocket Full of Rye recap

Financier Rex Fortescue is poisoned with taxine, with grains of rye found in his pocket. His wife Adele and the maid Gladys Martin are then killed in ways echoing a nursery rhyme. Inspector Neele investigates the family's money disputes and an old mining betrayal, while Miss Marple comes because she once trained Gladys. The rhyme and the MacKenzie grievance are partly camouflage. Rex's son Lancelot courted Gladys under a false name and induced her to place the poison in Rex's food; he then killed Adele and Gladys to secure the inheritance and prevent exposure. Gladys had mailed Miss Marple a photograph that reveals her supposed admirer as Lance. Jennifer Fortescue is separately exposed as Ruby MacKenzie, seeking redress for her father's ruin but not responsible for the murders. Lance is arrested.

Financier Rex Fortescue becomes violently ill at his London office and dies after being taken to hospital. Inspector Neele learns that he was poisoned with taxine, a substance associated with yew, and that grain was inexplicably scattered in his pocket. The inquiry moves to Yewtree Lodge, where Rex's younger wife Adele, elder son Percival, daughter Elaine, daughter-in-law Jennifer, and the domestic staff all have grievances or secrets. Rex's estranged younger son Lancelot is abroad but is expected home. The combination of poison, family money, and the rye suggests both a practical scheme and a deliberately planted symbol.

Adele Fortescue is poisoned with cyanide, and shortly afterward the maid Gladys Martin is found strangled outside with a clothes peg placed on her nose. The three deaths now resemble elements of a familiar nursery rhyme. Lance returns with his wife Pat and joins Percival in considering the family's business and inheritance. Suspicion touches Adele's lover Vivian Dubois, the self-possessed housekeeper Mary Dove, and several members of the Fortescue family. Miss Marple arrives because Gladys once worked for her and she feels responsible for discovering how a trusting young woman became part of the sequence.

Miss Marple and Inspector Neele trace the nursery-rhyme imagery toward Rex Fortescue's old partnership with Mr MacKenzie and a disputed African property called the Blackbird mine. MacKenzie's family had been taught to seek revenge after his ruin, suggesting that one of his children may be living under another name. Yet that history does not fully explain how taxine entered Rex's breakfast before the household knew he would die, or why Gladys was singled out. Miss Marple concentrates on the girl's recent secret romance and her eagerness to obey someone she trusted. The family inheritance and renewed value of Rex's old mining interests supply a more immediate financial motive.

Miss Marple proves that Lancelot Fortescue planned the murders. Using a false identity, he courted Gladys Martin and persuaded her to put taxine into Rex's breakfast while concealing its purpose. After returning, he poisoned Adele and strangled Gladys, adding nursery-rhyme details to redirect the investigation and remove those who could obstruct his control of the family assets and the Blackbird mine. Jennifer Fortescue is revealed as Ruby MacKenzie and had pursued a private revenge connected with her father's ruin, but she did not commit the killings. Before her death, Gladys sent Miss Marple a letter and a photograph of the man she loved; it identifies Lance behind the disguise. Lance is arrested, and the case closes with Miss Marple mourning Gladys's exploited innocence.

Miss Marple identifies Lancelot Fortescue as the murderer. Before returning home, Lance cultivated the inexperienced Gladys Martin under a false romantic identity and persuaded her to put taxine into Rex's breakfast without understanding that it would kill him. Lance then murdered Adele with cyanide and strangled Gladys, arranging details from the nursery rhyme to make the deaths seem linked to an old grievance. His aim was control of the family wealth and the valuable possibilities attached to the Blackbird mine. Jennifer Fortescue is revealed as Ruby MacKenzie, but her private acts of revenge and concealment did not include the murders. A letter and photograph Gladys sent to Miss Marple expose Lance's deception. He is arrested, and Miss Marple grieves that Gladys's trust was used against her.