The Woman in Cabin 10

The mystery Lo has been chasing since the first night of the Aurora's maiden voyage resolves into a murder-and-impersonation scheme orchestrated by the ship's owner, Lord Richard Bullmer. After being captured and locked below deck by the woman she'd seen through the peephole of cabin 10, Lo realizes while helping her wash up that the woman is not actually Bullmer's wife Anne, the Norwegian heiress dying of cancer who greeted Lo at dinner the first night. The woman is Carrie, a young mistress of Bullmer's whom he smuggled aboard and installed in cabin 10 under Anne's identity. The real Anne was murdered by Bullmer that first night; Carrie, manipulated into believing it was an accident, helped dispose of the body over the balcony rail — the splash and blood smear Lo witnessed. Bullmer has kept Carrie masquerading as Anne ever since so he can eventually inherit his wife's fortune.

Lo convinces Carrie that Bullmer is using her and will discard her once the inheritance scheme is complete. The two women, who discover a shared fondness for Winnie-the-Pooh, form a fragile alliance, and Carrie agrees to help Lo escape while the Aurora is docked at a small Norwegian village. The escape goes wrong when Lo, trying to evade Bullmer on deck, falls overboard into the freezing water. She swims to shore, seeks help at a hotel and from a local policeman, but flees both, convinced Bullmer's influence extends to them. She eventually finds refuge in a farmer's barn and is taken in before making her way back to London.

Back home, Lo reunites with her boyfriend Judah, and their earlier rift seems to mend; she suggests they take up his job offer and move to New York together. Scotland Yard later informs her that two bodies have been recovered from the sea: Bullmer's, killed by a gunshot wound that investigators determine was not self-inflicted, and the body of a woman. Lo assumes the second body is Carrie, but officials identify it as Anne, the wife Bullmer actually murdered — meaning Carrie may have survived. The book ends on an ambiguous note as Lo receives an anonymous bank transfer accompanied by a message referencing Winnie-the-Pooh, strongly implying that Carrie got away and is quietly repaying Lo for her help.

Lo Blacklock, a London travel journalist with a history of insomnia and alcohol use, is left rattled after a break-in at her flat that trapped her in her own bedroom, and her relationship with her boyfriend Judah is strained when the book opens. She lands a high-profile assignment covering the maiden voyage of the Aurora Borealis, a small luxury cruise liner owned by Lord Richard Bullmer. Aboard, Lo is placed in cabin 9, next to cabin 10, where she briefly meets a young woman before dinner and borrows mascara from her. At the welcome dinner she meets Bullmer and his visibly ill wife, Anne, a Norwegian heiress with cancer, along with other guests: her ex-partner and fellow journalist Ben, food critic Alexander, and photographer Cole. The woman from cabin 10 is notably absent from dinner.

That night, Lo hears a splash and glimpses a body vanishing into the water, plus a smear of blood on the glass divider by cabin 10. Ship security head Nilsson finds nothing amiss, tells her the cabin's occupant cancelled her trip, and implies Lo imagined it while drunk. Over the following days Lo's evidence keeps disappearing or being sabotaged — her mascara, a threatening message scrawled on her mirror, a water-damaged photo memory card, her phone — and she starts to suspect nearly everyone aboard, including Ben.

The truth emerges when Lo is captured and imprisoned after spotting and chasing the cabin 10 woman: the woman is Carrie, Bullmer's mistress, smuggled aboard to impersonate his wife Anne. Bullmer murdered the real Anne on the first night of the cruise and manipulated Carrie into helping dump the body, then had her pose as Anne so he could later inherit Anne's fortune. Lo persuades Carrie that Bullmer is using her, and the two bond over a shared love of Winnie-the-Pooh, leading Carrie to help Lo escape at a Norwegian port. The escape goes awry — Lo ends up overboard in icy water, flees people she no longer trusts, and eventually makes it home to London and back into Judah's arms, with the two considering a move to New York.

The book closes with Scotland Yard recovering two bodies from the sea: Bullmer, shot in a killing that wasn't a suicide, and a woman identified as the real Anne rather than Carrie. This leaves open the possibility that Carrie survived, reinforced by a mysterious bank transfer Lo receives with a Winnie-the-Pooh reference. Going into the next book, Lo has survived a harrowing ordeal that exposed a murder-and-fraud scheme, is reconciling with Judah, is weighing a move to New York, and is left with unresolved questions about whether Carrie is alive and who sent her the money — though Bullmer and the real Anne are confirmed dead.