Ruth Ware

Lo Blacklock, a travel journalist, is assigned to cover a luxury cruise on a small, exclusive ship. During the voyage, she believes she sees a woman being thrown overboard from the cabin next to hers—Cabin 10. However, all passengers are accounted for, and no one believes her claim that someone is missing. As she investigates further, Lo becomes increasingly isolated, unsure whether she is witnessing a cover-up or losing her grip on reality.