Laura "Lo" Blacklock, a determined investigative journalist recovering from a traumatic case, takes up what seems like a low-stakes assignment aboard a luxury superyacht — the Aurora Borealis — for a high-profile charity cruise hosted by wealthy philanthropist couple Anne Bullmer and Richard Bullmer.
During her first night on board, Lo ducks into an adjacent cabin — “Cabin 10” — to avoid unexpectedly running into her ex-boyfriend (who happens to be on the yacht too). Inside, she sees a strange blonde woman. Later, in the dead of night, she hears a scream and thinks she witnesses that woman being pushed overboard.When Lo reports what she saw, the crew and other passengers deny everything — no guest was assigned to Cabin 10, the room is empty, and no one is missing. Everyone insists she must be mistaken, casting doubt on her memory and mental state.

