Alice Pengelley visits Poirot in London, telling him she thinks she is being poisoned by her husband. When Poirot arrives in Cornwall the next day to investigate Mrs. Pengelley's charges, he is too late, and finds her dead.

A young woman is delivering a set of antique Napoleon miniatures to an American collector when they are stolen from her suitcase. Captain Hastings, under Poirot's guidance, sets out to find the thief.