一个让波罗耿耿于怀的失败的案例，有没有听说过？这就是了， 法国颇有声望的副部长保罗·戴鲁拉德在一次晚饭后突然倒地身亡，原因被认为是心脏病突发。 三天后，波罗受人所托前往死者住所进行暗访，在保罗·戴鲁拉丧生的书房里，波罗注意到，桌面上放着满满一盒巧克力，盒子是粉色的，而盖子却是蓝色的。 经过缜密的分析，波罗宣布：他找到了真凶！ 当然，最后的结果是：真凶另有其人.

On his doctor's orders Poirot has gone to stay in the seaside resort of Brighton, where he is frequently mistaken for Lucky Len, who gives out money on behalf of a newspaper to people who recognize him. Poirot is staying at the Metropolitan hotel, as are Mr. Opalsen, a theatrical producer, and his wife who is an actress starring in a play at a local theatre. A set of valuable pearls which Mrs. Opalsen wears in the play is stolen from her room, and suspicion falls on her maid Celestine, who was in the room next door. Celestine loves Andrew, the impoverished young author of Mrs. Opalsen's play but they cannot afford to get married and she is accused of taking the jewels to finance their marriage. Poirot solves the case and unmasks the real culprit, being rewarded by Opalsen and getting a bonus when he identifies the real Lucky Len.