El testigo mudo

Miss Arundell is a wealthy elderly spinster whose nephews wish to see dead so they can vent their financial straits. When she has an accident falling down the stairs, everyone blames it on the rubber ball left by Bob, her dog. But the old woman is suspicious, and she thinks that they have tried to assassinate her. On April 17 she writes a letter to Poirot requesting her help, but he does not receive it, mysteriously, until June 28. By then, Miss Arundell has been murdered, and the only witness to the crime is Bob, her beloved pet. An almost perfect crime that only Poirot can solve.