Head of Homicide Jens Møller and his team of dedicated investigators tirelessly work what became the most talked-about murder case in Danish history. On paper, it looked like a very simple case: a man and a woman take a trip on a submarine. The man comes ashore alone. When the submarine is raised, the police find traces of blood from the young woman in the otherwise thoroughly cleaned hull. It quickly turns out, however, that the case is not quite so simple. There is no body, no cause of death, no motive, and no murder weapon.
A submarine carrying a journalist and the submarine's inventor disappears. When the submarine is found, only the inventor is rescued. Jens Møller and his investigation team must decide how to approach the case, as the journalist is still missing.
Jens is under pressure from journalists chasing news of the case. The journalist's parents assist the police in their work, and forensics work to find clues in the capsized submarine - without any luck. Then the case suddenly takes a dramatic turn.
While the forensic team works, Jens and his team wait for answers. Jens goes to Sweden to confirm the journalist's death to her parents while divers search for more clues-but Jens then has a radical idea that might help the investigation.
Jens brings in cadaver dogs that can locate bodies more than 20 meters below sea level. Although the dogs mark the areas quite accurately, the divers find nothing. Then Jens hears from an oceanographer who offers previously unknown information.
The case is coming together, but Jens and his team have no hard evidence. Chief Prosecutor Jakob Buch-Jepsen stresses they must find motive and cause of death. Jens calls a surprise press conference and the suspect's computer reveals grisly secrets.
Chief Prosecutor Jepsen makes it clear to Jens they need more evidence. Investigator Porse refuses to drop the case, and after nearly 6 months she finds key evidence. Jens realizes that his time as Head of Homicide is coming to an end.
