Dumb Witness recap

Poirot receives a delayed letter from Emily Arundell, an elderly woman who wrote after falling down the stairs at Littlegreen House. By the time he investigates, Emily has died of what was called liver disease and has disinherited her family in favour of her companion, Wilhelmina Lawson. Poirot studies Emily's indebted nephew Charles, his sister Theresa and her doctor fiance, and their cousin Bella Tanios with her husband Jacob. The fall was blamed on the terrier Bob's ball, but Bob's behaviour shows the scene was arranged. Poirot discovers that Bella stretched a cord across the stairs and later killed Emily with phosphorus, hoping to inherit for herself and her children. The poison also explains the glow seen during a spiritualist séance. Bella had tried to turn suspicion toward her husband; when Poirot confronts her, she takes her own life and leaves an admission. Lawson shares much of the inheritance, and Hastings provides Bob with a home.

Poirot receives a letter dated two months earlier from Emily Arundell of Littlegreen House, Market Basing. Emily writes guardedly about a recent accident and makes clear that she is worried, though she never directly accuses anyone. Poirot and Hastings discover that she has since died, officially from the liver trouble for which she was already being treated. Before her death she had survived a fall down the stairs, attributed to stepping on the ball of her wire-haired terrier Bob. The letter's delay and Emily's caution persuade Poirot that the fall was not accidental. He enters the household under a pretext, since the family believes there is nothing left to investigate.

Emily's relatives had gathered at Littlegreen House shortly before the fall. Her nephew Charles is openly in debt, his sister Theresa has expensive tastes and an engagement to the ambitious Dr Donaldson, and their cousin Bella Tanios is trapped in a strained marriage to Dr Jacob Tanios. All expected to benefit from Emily's estate. Instead, after the staircase incident Emily made a new will leaving almost everything to her nervous companion, Wilhelmina Lawson. The change gives Lawson a clear financial advantage but also suggests Emily wanted to prevent her family profiting from her death. Poirot studies the stairs, Bob's routines, and the household's movements, treating the supposed dumb witness as more dependable than several human accounts.

Poirot and Hastings interview the possible heirs and find motive everywhere but no simple fit. Charles and Theresa make no secret of needing money. Donaldson has medical knowledge and a practical interest in Theresa's prospects. Bella describes her husband as controlling and dangerous, while Jacob presents himself as a doctor trying to protect an unstable wife and two children. Lawson alternates between self-importance and fear, easily influenced by whoever last spoke to her. The local Tripp sisters recount a séance held at Littlegreen House, during which a strange luminous appearance surrounded Emily. The family accepted the death that followed as natural, but Poirot considers whether the apparent return of an old illness was deliberately produced.

The physical reconstruction strengthens Poirot's belief that the staircase fall was engineered. Bob did not normally leave his ball in the position where Emily supposedly stepped on it, and marks around the stair suggest a cord could have been stretched across the passage. Emily's survival explains both her fear and the rapid change to her will. Poirot also investigates the medicines, domestic supplies, and medical symptoms surrounding her later death. The séance is treated as evidence rather than superstition: the glow seen around Emily may have had a chemical cause. At the same time, tension inside the Tanios marriage increases, with Bella seeking protection and Jacob warning that her account cannot be accepted at face value.

Poirot begins to separate greed from the capacity to carry the plan through. Lawson inherited but lacked both the nerve and the foresight behind the staged accident. Charles and Theresa wanted money but their behaviour after Emily's death does not explain the careful use of Bob's ball. Donaldson's knowledge is relevant without proving that he used it. The key sequence is now clear: a first attempt made to resemble a household mishap, Emily's secret appeal to Poirot, a changed will, and a later death whose symptoms resembled her known liver complaint. Poirot identifies phosphorus as the likely poison and connects it to the strange light seen at the séance. He prepares to confront the person who could exploit both family prejudice and medical ambiguity.

Poirot identifies Bella Tanios as Emily Arundell's murderer. Bella arranged the staircase fall by stretching a cord and planting Bob's ball so the terrier would be blamed. After Emily survived, changed her will, and wrote to Poirot, Bella administered phosphorus; its effects were mistaken for liver disease, and it also produced the luminous appearance observed during the séance. Bella hoped to secure money for herself and her children and tried to shape suspicion around her husband Jacob. Bob's habits disprove the staged accident, while the medical and household evidence support the poisoning. Poirot clears Lawson, Charles, Theresa, Donaldson, and Jacob of the murder. Rather than face public arrest and expose her children to the trial, Bella takes her own life and leaves an admission. Lawson remains the legal heir but voluntarily shares the estate with the family. Hastings takes responsibility for Bob, whose behaviour supplied the silent evidence that opened the case.

Poirot proves that Bella Tanios killed Emily Arundell. Bella had stretched a cord across the stairs and placed Bob's ball nearby so that Emily's first fall would be blamed on the dog. When Emily survived and changed her will, Bella later poisoned her with phosphorus, producing symptoms that passed as a recurrence of liver disease. The luminous effect witnessed during the Tripps' séance came from the poison rather than a spirit, while Bob's habits showed that the ball had been planted. Poirot eliminates Charles and Theresa despite their greed, Dr Donaldson despite his knowledge, Miss Lawson despite inheriting, and Dr Tanios despite Bella's efforts to make him appear threatening. Faced with Poirot's conclusion and unwilling to expose her children to a public trial, Bella takes her own life after leaving an admission. Poirot treats the death as the final consequence of the case rather than a victory. Miss Lawson, who retains Emily's estate under the valid will, chooses to distribute substantial shares to the family. Bob is given a secure home with Hastings, who has been his firm advocate throughout the investigation.