The book: The Woman in Cabin 10 by Ruth Ware
The hook: In this tightly wound story reminiscent of Agatha Christie's works, a journalist, Lo, is sent to cover a brand new luxury cruise on the North Sea with only a handful of cabins before it opens to the public. Despite her plush surroundings, Lo soon begins to suspect that not all is as it seems, especially after she witnesses a woman being thrown overboard. The only problem? No passengers are missing the next morning, and no one believes her. Can she solve the mystery of what really happened before it's too late?
Fear factor: To Ware's credit, this book is immensely claustrophobic, and might put you off of cruise ships for life.