This was meant to be the 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. But the records show that no-one ever checked in to that cabin, and no passengers are missing from the boat.