A young woman has disappeared without a trace and her boyfriend, a beat cop, is convinced she was murdered.

Two seemingly unrelated cases bring Germany and Sweden together to catch a serial killer. In Kiel, a man jumps into a bathing lake - and is impaled by bamboo sticks. For Borowski and Sarah Brandt, it is initially not clear whether it is the act of a madman who accidentally finds his victims. Or did someone want to punish the dead?

A desperate call alerted the Kiel police emergency number: "He's in my apartment. He just comes through the wall." But for Carmen Kessler, any help comes too late. The young woman is found brutally murdered in her apartment.

The Kiel author Dirk Sauerland is found dead on his yacht. Sauerland was known beyond the borders of Kiel. In recent months he had been working on a spectacular disclosure story.

Jingle bells on the Kiel Fjord: while Commissioner Borowski and his colleague Sarah Brandt are celebrating Julklapp in the Presidium, a murderer is preparing a dark crime in neighboring Schleswig. At the Lucia Festival parade at a Danish school, a man suddenly caught fire. Kriminalrat Schladitz, who spent his childhood in this place, becomes an involuntary witness to the brutal attack. The dead man, Michael Eckart, was the headmaster here and is a member of the Danish minority. At first everything indicates that the murderer can be found in the immediate vicinity of the dead man.

The geriatric nurse Sabrina Dobisch witnesses a traffic accident and bravely tries to save the life of the young pedestrian Christian van Meeren. She then accuses the driver Doris Ackermann of premeditated murder. While Sabrina is celebrated as a courageous rescuer and enjoys public attention, Inspector Borowski remains skeptical: Apart from the testimony, nothing indicates a capital crime. Until his colleague Sarah Brandt finds a gun in Doris Ackermann's glove compartment. Is there a connection between Christian van Meeren and Doris Ackermann? And what role does the piano teacher André Rosenthal play, who often spent time near the dead man?

On a nocturnal boat trip by the company Marex, the lawyer Jens Adam is spectacularly shot. His body disappears into the sea. Marex is a world leader in the mining of raw materials in the deep sea, specializing in rare earths. By mining these metals, which are found in every mobile phone, Marex wants to land a business worth millions. Does Adam's death have anything to do with the killing of an environmentalist who was protesting the destruction of the ocean floor? Jens Adam's wife Marte could also have killed her husband out of jealousy, because he had several affairs.

The severed head of a young man is found in Mundsforde, a small village near Kiel. Before his violent death, 20-year-old Mike was apparently addicted to the drug crystal meth. Inspectors Klaus Borowski and Sarah Brandt investigate the drug scene in Kiel. After a manhunt call, Rita, the girlfriend of the deceased, gets in touch. She tells the inspectors about her love for Mike, a story full of hope for a new life, intoxication and ecstasy. Although recently clean, Rita refuses to cooperate with the police. Rita reminds Borowski of his daughter Carla. He puts pressure on Rita and promises to protect her. In her distress, Rita accuses two dealers - and thereby puts herself in danger.

The 60-year-old alcoholic Onno Steinhaus is found dead in a working-class district of Kiel. Steinhaus had a criminal record for pedophilia and, as Borowski and Brandt quickly find out, lived in complete isolation. Ironically, however, a group of children seemed to have gone in and out of the dead man. Apparently they exploited the dead man's desires, but - as they claim at least - never complied with his wishes. The police officer responsible for the district, Thorsten Rausch, seems to have capitulated in view of the social neglect in his area. Sarah Brandt's investigations bring to light a video that shows a boy - Timo Scholz - in a catchy situation with Onno Steinhaus. Timo denies having been abused. Borowski has to observe that Sarah Brandt is conspicuously often trying to get close to her police colleague Rausch.

A confused woman is found on the Kiel Fjord. Her statements give reason to fear that the notorious murderer of women, Kai Korthals, has reappeared. Inspector Brandt informs her colleague Borowski about the serial killer, with whom she once had traumatic experiences. Borowski finds the new case highly inconvenient. He's in love and wants to get married. But when his bride disappears without a trace, he has to ask himself whether the murderer has returned because of him.

At the heart of the story is a student who accuses her brother of murdering another student. The next morning, Maria's body is actually recovered from the fjord. Investigative duo Klaus Borowski and Sarah Brandt find clues as to why Julia's brother could have committed the crime, but Julia's betrayal cannot be explained by the commissioners. Only when they discover that she has secretly converted to Islam does light seem to be slowly coming into the dark. But Borowski and Brandt are not alone in their research: the state protection department at the state criminal office around head Kesting apparently pursues its own unscrupulous interests.

Jürgen Sternow, head of the cyber crime department at the Kiel State Criminal Police Office, was the victim of a murder attack. It is reasonable to assume that the perpetrator is to be found in the area of rapidly growing cybercrime. Commissioners Borowski and Brandt are entrusted with the investigation by the responsible public prosecutor. While Borowski first has to acquire special technical knowledge, Sarah Brandt is in her element as a former hacker. But how do you hunt a perpetrator who has no relation to the victim and who knows all the tricks to hide in the Darknet?

There is a state of emergency shortly before the Kiel Week. Three million guests from all over the world are expected to celebrate the largest summer festival in Northern Europe. Now, of all times, a treacherously murdered woman is found in an empty apartment in the middle of the city center. There is no trace of the perpetrator, who had evidently set himself up in hiding for months. When inspector Borowski looks around the victim's apartment, he suddenly finds himself in front of a wall of fire. Roman Eggers and the inspector face each other for a moment. Eggers tries desperately to annihilate the consequences of his crime - and saves Borowski at the last moment. Then he disappears into the anonymity of the city, which is slowly filling up with people. When another body is found, Borowski and Brandt are alarmed: Are they dealing with a serial killer?