As Dorn and Lessing investigate the death of a woman during a robbery, it becomes clear that all is not as it seems.

A man falls from the top floor of a luxury hotel in Vienna. The Iranian diplomat and nuclear physicist Dr. Bansari apparently committed suicide. But why did he buy expensive opera tickets for the same evening? Moritz Eisner and his colleague Bibi Fellner want to investigate the matter, but the Iranian embassy and the Austrian Foreign Ministry immediately get involved. The case is subject to the strictest secrecy - the dead man's laptop and cell phone are confiscated. The two investigators are annoyed, but do not give up. The hotel's surveillance video leads them to the trail of the shady lobbyist Johannes Leopold Trachtenfels-Lissé. He has arranged a secret deal with Dr. Bansari. Eisner and Fellner find out that the case involves valves and pumps that are needed for nuclear reactors. A trainload of the high-quality components is to be sent to Iran via third countries. For the two investigators, a race against time begins - and against the Israeli secret service Mossad.

The head of the Dortmund neo-Nazi scene is found murdered in a suspected act of vengeance.

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.

A young man's disappearance in 1968 leads Eisner and Fellner to a present-day mystery on the Czech border.

A case involving a missing seven-year-old resurfaces ten years later.

An apartment bathroom is covered in blood with no body in sight.

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.

The team gets involved in the investigation of a seriously injured man found in front of a Dortmund clinic.

A tragic accident occurs in a chemical factory. Roswita, the godchild of Ernst Rauter, Moritz Eisner and Bibi Fellner's superior, is a victim of the chemical accident.