In "Passenger 23" the focus is on police psychologist Martin Schwartz, who lost his wife and son during a trip on a cruise ship five years ago - no one could tell him what exactly happened. Now he is called back to the transatlantic liner from back then. There is evidence of what happened to his family. Martin never wanted to set foot on a ship again - and yet he follows the tip and learns that a girl who disappeared on board weeks ago has reappeared. With his son's teddy bear in his arms...