When Head of Homicide for Copenhagen Police Jens Møller comes in for the morning briefing, an investigator reports on a strange case. A homemade submarine carrying a female Swedish journalist and the submarine's inventor has gone missing. When the submarine is located later in the day, only the submarine's inventor is rescued before the submarine suddenly sinks. Now Jens Møller and his team of investigators must quickly decide how to approach the case, as the journalist is still missing and the submarine is at the bottom of the sea.

While the forensic team works, Jens Møller and his team of investigators are waiting for answers. Have they found conclusive evidence that the Swedish journalist is dead, and if so, has a crime been committed? Jens Møller goes to Sweden to confirm the journalist's death to the grieving parents while Navy divers search the seabed in the Sound for more clues. Jens Møller then has a radical idea that might help the investigation.