The Woman in Cabin 10 by Ruth Ware

Lo is a travel writer on board a luxury cruise ship. In the middle of the night, she hears a scream and the thud of a human body falling into the ocean. She alerts security, but no one is found missing on the ship. Was it just because she'd been drinking too much? Is she going crazy?

A kinda thriller of a read, but just so-so, in my opinion.