The Mysterious Affair at Styles, with eBook recap

While staying with his friend John Cavendish at Styles Court, wounded veteran Arthur Hastings witnesses the death of John's wealthy stepmother, Emily Inglethorp, from strychnine poisoning. Suspicion first falls on her unpopular younger husband Alfred, but the evidence is strangely contradictory. Hastings calls on his Belgian friend Hercule Poirot, who studies the household's rivalries, financial dependence, medicines, wills, and carefully planted clues. John is eventually arrested and tried, but the case against him collapses. Poirot proves that Alfred and Emily's companion Evelyn Howard were secret accomplices: their conspicuous hostility helped conceal their partnership, and they manipulated Emily's medicine and the timing of the poison while trying to make Alfred look too obviously guilty to be convicted. Both conspirators are arrested, John is exonerated, and the strained Cavendish marriage begins to heal.

Army officer Arthur Hastings, home on sick leave during the First World War, meets his old friend John Cavendish and is invited to Styles Court. The estate belongs to John's wealthy stepmother, Emily Inglethorp, who supports John, his wife Mary, John's younger brother Lawrence, and the orphaned Cynthia Murdoch. Emily has recently married the much younger Alfred Inglethorp, whose manner and influence have made him unpopular. Emily's companion Evelyn Howard openly accuses Alfred of pursuing Emily's money and leaves after a bitter quarrel. On the following day Emily appears distressed after an argument whose other participant Hastings cannot identify. That night the household is awakened by her cries. Her bedroom is locked, and when the doors are forced she suffers violent convulsions and dies. The circumstances suggest poison rather than natural illness.

Hastings asks his friend Hercule Poirot, a former Belgian detective now living nearby as a refugee, to investigate Emily Inglethorp's death. Poirot examines the locked bedroom, a stain on the floor, the fireplace, a damaged dispatch case, and the remains of drinks and medicines. He questions the household about Emily's movements, a recent quarrel, and a paper she may have burned. The doctors conclude that strychnine caused her death. Alfred, already distrusted by the family, appears to have had both a financial motive and an opportunity, yet he claims to have been away from Styles and is reluctant to explain himself. Poirot insists that the timing and physical evidence must be understood before anyone is accused, and he is troubled by details that seem designed to point too directly at Emily's husband.

At the inquest, evidence about strychnine, Emily's medicine, and a purchase made in Alfred's name strengthens the appearance of murder. The household's finances and Emily's habit of revising her will supply possible motives for more than one person. Alfred produces an alibi only after pressure, frustrating those who expected his arrest. Poirot continues to reconstruct the household's movements and the handling of Emily's coffee and medicine. He also follows small discrepancies in testimony instead of treating any single clue as decisive. Hastings grows impatient with Poirot's secrecy, especially when the detective seems more interested in domestic details than in the obvious suspect, but Poirot maintains that the apparently simple case has been deliberately arranged to mislead.

Fresh discoveries shift suspicion among the residents of Styles. The police examine Cynthia's work in the dispensary and Dr Bauerstein's specialist knowledge, while private tensions involving Mary and John Cavendish emerge. Poirot distinguishes these concealed personal matters from evidence of murder, though Hastings repeatedly confuses the two. A reconstruction of the night shows that several people had reasons to move quietly through the house and that the poisoned dose cannot be explained by the most obvious account. Police attention eventually turns away from Alfred and toward John, against whom damaging material accumulates. Poirot remains dissatisfied: the evidence can support an arrest, but he believes an unseen pattern connects the missing and altered objects.

John Cavendish is arrested and prosecuted for Emily's murder. The case against him combines financial motive, the household quarrel, incriminating objects, and the claim that he had access to the poison. Mary supports him despite the strain in their marriage. Under examination, however, the prosecution's neat account proves less secure than it first appeared, and important testimony can be interpreted in another way. John is acquitted. Poirot still refuses to name the murderer until he can supply proof rather than suspicion. He returns to the sequence involving Emily's medicine and to a final missing link among the papers and household clues, convinced that the real plan depended on manipulating both the poison's timing and the investigators' expectations.

Poirot finds the last documentary clue and assembles everyone at Styles. Alfred Inglethorp and Evelyn Howard were secretly working together; their loud public hostility was camouflage. They arranged for strychnine already associated with Emily's treatment to become lethal at a chosen time and planted a trail that would make Alfred appear the immediate culprit. Their design relied on his being arrested on an incomplete case and then acquitted, preventing a later trial for the same crime. Poirot blocked that premature arrest until the conspiracy could be proved. Alfred and Evelyn are taken into custody, while John is fully cleared. The disclosures also resolve the household's private misunderstandings: John and Mary reconcile, and Lawrence and Cynthia move toward a life together. Hastings sees the case as the beginning of Poirot's English career.

Poirot gathers the household and explains that Alfred Inglethorp and Evelyn Howard planned Emily's murder together while publicly acting like enemies. They exploited the delayed effect of strychnine already present in Emily's medicine and arranged misleading evidence so Alfred would appear obviously guilty at first. Poirot prevented an early arrest because an acquittal would have protected Alfred from being tried again. A revealing letter and the accumulated physical clues finally establish the conspiracy, and Alfred and Evelyn are arrested. John Cavendish, previously prosecuted for the crime, is cleared. The crisis also breaks down the reserve between John and Mary, who reconcile, while Lawrence and Cynthia acknowledge their attachment. Hastings believes Poirot has restored order at Styles, though Poirot notes that human happiness, rather than detection alone, is the best result of the case.