The mysterious dissapearance of his family continues to torment police psychologist Martin Schwartz (Lucas Gregorowicz). Five years ago, his wife Nadja and his son Timmy did not return from their trip on the cruise ship Sirius. Five years that have turned Martin into a human wreck. Now it seems his past is catching up with him. Yet again a mother and her child have dissapeared at sea without a trace. Exactly the same way! However this time there is a difference: the child has turned up again - with Timmy's teddy bear in her arms!

Although Martin had never wanted to set foot on another ship again, he pursues this strange clue and boards the gigantic cruise ship and sets sail from Southampton to New York. The ship's owner Yegor Kalinin (Pjotr Olev) does not make a secret of the fact that the reappeared child and the ensuing complications do not suit him in the least. This case must be kept secret at all costs. Captain Daniel Bonhoeffer (Oliver Mommsen) ensures, that the girl is hid below decks in the quarantine station in the ship's belly - for her own safety. Little Anouk (Annalee Ranft) appears to be traumatized. Martin is battling his own pain and memories of his own son. With the help of the doctor Elena Beck (Picco von Groote) he tries to win Anouk's trust. Martin suspects that Anouk knows what became of her mother - and possibly also of Nadja and Timmy. However Anouk stays reserved, hardly speaks. And what she says does not make sense to Martin.

Among the Sirius' guests are also Julia Stiller (Liane Forestieri) and her daughter (Lisa (Mercedes Mueller). Lisa's godfather is Daniel Bonhoeffer. It seems that he had made this luxurious trip possible for her. Julia however is worried. Her daughter seems distant and sad. When Julia receives a video, in which Julia can be seen prostituing herself, she is afrait that her daughter plans to take her own life during the trip. As a matter of fact, there is a completely different plan, that could endanger Julia's life.

Deep below decks Naomie Lamar (Kim Riedle), Anouk's mother, huddles in a dark cell. Noone can hear her screams. Somewhere on the ship a murderer is busy and tortures prisoners. It is just a question of time when he attacks yet again...

Martin tries his utmost to find him and to finally know all the truth.