Mrs. Otterbourne’s flair for the dramatic gets the better of her. She is undone by her vices: first she saw something she shouldn’t have because she was getting alcohol. And here, she takes so long to tell her story (because she loves that spotlight) that someone manages to shoot her before she can reach the end. Out of all the deaths, hers is the most comic. Poirot and Race were even joking earlier about how they wished Mrs. Otterbourne had been murdered instead—of course never suspecting that such a thing would actually happen. That someone killed Mrs. Otterbourne just before she was about to reveal who went into Louise’s cabin implies that this information is crucial for solving Louise’s murder—and that whoever killed Mrs. Otterbourne is likely the same person who killed Louise.