The Woman in Cabin 10 by Ruth Ware
This was meant to be perfect trip. The Northern Lights. A luxury press launch on a boutique cruise ship.
A chance for travel journalist Lo Blacklock to recover from a traumatic break-in that has left her on the verge of collapse.
Except things don't go as planned.
Woken in the night by screams, Lo rushes to her window to see a body thrown overboard from the next door cabin. Byt the records show that no-one ever checked into that cabin, and no passengers are missing from the boat.
Exhausted and emotional, Lo has to face the fact that she may have made a mistake - either that, or she is trapped on a boat with a murderer...