Twelve-year-old Sven Reimer (Daniel Spies) is found dead in a forest at a children's holiday camp near Regensburg. Commissioner Ellen Lucas (Ulrike Kriener) and her team are called to the crime scene. At first it all looks like a tragic accident, but investigators quickly uncover forensic evidence pointing to murder. The Lucas team is investigating under high pressure. Lars Berger (Aljoscha Sena Zinflou), one of the supervisors, has no alibi for the time of the crime and quickly becomes a suspect. Berger is from Africa, and Stefanie (Mia Sophie Wellenbrink), daughter of investigator Martin Schiff (Alexander Lutz), who is also spending her holidays at the summer camp, claims to have seen a black man near the crime scene. The children in the camp play the game: 'Who's afraid of the black man'.
But then the homeless Antholz (Peter Kurth), who was the victim of an accident near the quarry, is picked up. The forensic technology finds clear traces that convict Antholz as the perpetrator. Ellen sharply interrogates Antholz. Antholz admits to having found the boy lifeless in the forest, but vehemently denies the crime. Unbelievable for everyone, Antholz dies – during the interrogation – as a result of his accident. The case is closed for Chief Inspector Noethen (Michael Roll), but when Inspector Lucas discovers discrepancies in the profile of the perpetrator, she researches on her own. She checks into the Donauterrassen inn, which is located directly at the scene of the crime. There she recognizes the dark machinations of the inn owner Jürgen Müller (Bernd Tauber) and his daughter Katja (Alice Dwyer).
But the head of the Schweiger holiday camp (Robert Gallinowski) is behaving conspicuously, and supervisor Lars continues to refuse to reveal his alibi. After Ellen Lucas observes that the foster child Tim (Sandro Ianotta) reacts anxiously, she turns to the boy. What does Tim know, and what's up with the magic stone that disappeared without a trace after Sven's death? Tim, who, like his friend Sven, is a child in an

Four teenagers riot in the old town of Regensburg and threaten a younger couple. Max (Tilo Prückner) and Rike (Anke Engelke) rush to the victims' aid, and Rike is badly injured. Max takes up the pursuit of the young people. A short time later, Commissioner Lucas is called to a crime scene where the body of the only sixteen-year-old student Sebastian Holzinger (Martin Stürhrk), one of the four young people, has been found. Sebastian died as a result of a brutal fight in which Max, who is suspected of having committed a crime, was apparently also involved. Inspector Lucas' investigations initially focus on the other three students: Michi Schmidbauer (François Goeske) and his friends Miro Kovac (Edin Hasanovic) and Karli Sammer (Christian Reinhardt).
Under Sebastian's management, the boys run the Internet portal "pain attack", on the site of which videos recorded with mobile phones are displayed. "Happy slapping", as it is called in young professional jargon, fun films, but also violent videos in which mainly rich Regensburgers are denounced. OnA fragmentary and distorted film is found on the mobile phone of the murdered student Sebastian. The reconstruction of the video reveals a shocking truth: the high school student Diana (Nadja Bobyleva) was apparently sexually harassed by several young people, including Sebastian. For Commissioner Lucas the key to solving the case, but Diana, who has a strange love affair with Basti, remains silent - out of fear or solidarity - persistently. Then the investigators received the news that Günter, (Mathias Herrmann) the father of the dead boy, kidnapped the student Karli. He is firmly convinced that he has his boy's killer in his hands and threatens vigilante justice. Miro contradicts this theory and once again testifies that Max was the perpetrator, so that inspector Lucas has no choice but to as arresting their landlord. Then she gets wind that the students are planning a final coup. The action is to take place on a remote Danube bridge. Inspector Lucas rushes to the scene. Will she be able to prevent the impending catastrophe?