"The Woman in Cabin 10" is a psychological thriller novel by author Ruth Ware. The story follows Lo Blacklock, a travel journalist who embarks on a luxury cruise. During the voyage, she witnesses what she believes is a woman being thrown overboard from the adjacent cabin. As Lo investigates, she discovers that the woman in cabin 10 is missing, and no one on the ship seems to acknowledge her existence. The tension escalates as Lo grapples with her own sanity while trying to uncover the truth, leading to a suspenseful and gripping narrative.