Every year, around 20 people mysteriously disappear from cruise ships at sea. No one has ever returned. Until now.

Martin Schwartz, a police psychologist, lost his wife and son five years ago. It happened during a vacation on the cruise ship "Sultan of the Seas" - no one could tell him what exactly happened. Since then, Martin has been a psychological wreck, numbing himself with high-risk undercover operations.

In the middle of an assignment, he receives a call from a strange old lady who claims to be a thriller author: he must absolutely get on board the "Sultan," as there is evidence of what happened to his family. Martin vowed never to set foot on a ship again - yet he follows the lead and discovers that a girl who disappeared weeks ago on the "Sultan" has reappeared, holding his son's teddy bear in her arms.