Race examines Louise’s body and tells Poirot she has been dead for about an hour, stabbed through the heart. In her hands, she’s holding a fragment of a thousand-franc note, leading Race to conclude that perhaps she was blackmailing the murderer. Poirot laments that they didn’t think of this sooner. He doesn’t find anything particularly significant about the fact that Louise was holding French money, since many travelers carry a mixture of currencies. He imagines the murder happened while she was in the act of counting her blackmail money. They agree the killing of Louise suggests a very bold criminal.
While characters like Linnet and Mrs. Otterbourne are meant to satirize the upper class, the book’s depiction of the lower-class maid Louise could be read as a classist. Many characters in the story are greedy, but Louise is among those punished the most harshly for it. She is portrayed as nothing more than a low-life blackmailer and is arguably treated less sympathetically than the actual murderer. Still, her death fits with the pattern of characters in the story being undone by their own flaws.
Race calls in Dr. Bessner to examine Louise’s body. He confirms that she has been dead for about an hour. Then, after walking with Poirot and Race back to his own cabin, Bessner notes that the murder weapon was very similar to a surgical knife, like the ones Dr. Bessner himself has. When they ask if perhaps one of Bessner’s knives is missing, he becomes indignant but checks and confirms they’re all accounted for. Race and Poirot depart, with Race muttering something and leaving Poirot alone.
A surgical knife is an unusual murder weapon and definitely suggests improvisation instead of careful planning. Dr. Bessner is an obvious candidate—perhaps too obvious. Simon might also know about the knives, but he’s still out of commission in Bessner’s cabin.
Poirot hears Jacqueline and Rosalie talking in Rosalie’s cabin, with the door open. He asks them if they’re talking of scandal, but an unusually happy Rosalie says they’re just comparing lipstick. Poirot reveals what he just found out—that Louise has been killed and that, what’s more, Poirot believes Louise had seen someone enter and leave Linnet’s cabin the night of the murder.
Agatha Christie had a dark sense of humor, and there is a running joke in the book about Rosalie’s happiness always being suddenly interrupted by bad news—in this case, a murder.
Cornelia comes upon the group and cries out to Jacqueline that another terrible thing has happened. As those two talk, Poirot and Rosalie move out of earshot, and Poirot asks her why she didn’t tell him about her small-caliber pistol. She’s indignant and shows him her handbag to prove there’s no pistol inside. She asks Poirot what he’s driving at, so he muses that perhaps when she was out on the stern the previous evening, she saw a man come out of Linnet’s cabin and then enter one of the two end cabins. He adds that perhaps she’s afraid to say so because she doesn’t want to be killed. But after a slight hesitation, Rosalie continues to deny that she saw anyone.
Rosalie has already been caught lying to Poirot, so there is reason to suspect that she’s not being truthful when she claims that she doesn’t have a pistol. Still, if it’s a lie, it’s a bold one, given that she knows her bag was already searched. Poirot seems to have a strong theory about what it is that Rosalie saw and is hiding from him, but because she isn’t willing to admit it yet, the audience is also kept out of the loop.