Quick recap
Wealthy Emily Arundell falls down the stairs, and everyone blames the dog Bob's ball. She suspects otherwise and writes to Poirot, but the letter arrives two months later, after she's dead. Her will left everything to her companion, Minnie Lawson, and nothing to her nephews and nieces. Poirot and Hastings go to Market Basing and find someone had strung a thread at the top of the stairs. At a séance, witnesses saw a glowing haze coming from Emily's mouth. It was phosphorus, the poison that killed her. The culprit is her niece Bella Tanios, who wanted the money and meant to leave her husband. Exposed, she takes her own life.
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