Five years ago police psychologist Martin Schwartz lost his wife and son. They were holidaying on a cruise ship when they simply vanished, the case written off as a straightforward murder-suicide. They are not the only parent-and-child pair to have disappeared from the ship in recent years – and yet, the authorities seem unconcerned. But when a missing girl reappears – carrying Martin's son's beloved teddy bear – the police won't be able to avoid the truth that something sinister is lurking on board...

Five years ago police psychologist Martin Schwartz lost his wife and son. They were holidaying on a cruise ship when they simply vanished, the case written off as a straightforward murder-suicide. They are not the only parent-and-child pair to have disappeared from the ship in recent years – and yet, the authorities seem unconcerned. But when a missing girl reappears – carrying Martin's son's beloved teddy bear – the police won't be able to avoid the truth that something sinister is lurking on board...