throw it away. Poirot told her that he had completed his investigation and the matter was closed. Madame Déroulard died a week later of her infirmities. Poirot considers his mistakes. The mother's poor eyesight would cause her, and only her, to swap the lids. He misread the psychology of a murderer – Saint Alard would never have kept the empty bottle had he been guilty. Poirot told Hastings to remind him with the phrase chocolate box, if he seemed conceited. Then, he unconsciously goes on to boast about his successes. Hastings hesitates, considers, then graciously refrains from comment. "The Submarine Plans" Poirot is urgently summoned late at night by special messenger to 'Sharples', the home of Lord Alloway, head of the Ministry of Defence and a potential future Prime Minister. Arriving with Hastings, he is introduced by their host to Admiral Sir Harry Weardale, the First Sea Lord who is a guest at Sharples together with his wife and son, Leonard. The secret plans for the new 'Z'-type of submarine were stolen some three hours earlier. The facts of the case are that the ladies of the party – Mrs Conroy and Lady Weardale – retired to bed at 10:00 pm as did Leonard Weardale. Lord Alloway instructed his secretary, Mr Fitzroy, to move the various papers that he and the Admiral would require for their evening's work from the safe out to the table in the study, while the two men walked on the terrace and finished their cigars. Lord Alloway fancies that as they turned back on the terrace he saw a shadow move away from the open French window that leads into the study, although the Admiral is dismissive of this idea. Going into the study, they discovered the submarine plans were missing. Fitzroy claims to have been distracted by a scream outside the study. He went out to find Mrs Conroy's maid standing on the stairs, and she claimed that she had seen a ghost. It was then that the plans were probably stolen. Poirot examines the grass outside the study window and finds no trace of footprints, even though it rained earlier in the evening. That means someone in the house is responsible. He questions the household, although at Lord Alloway's insistence, he does not reveal to them that the plans have been stolen. Lord Alloway points out that Fitzroy is discounted. His secretary has