The psychology lecturer and family man Bernd Stach, convicted of murder, is able to escape from prison after attempting suicide. While the manhunt is already running for him, he already has Ellen Lucas in his sights. She led the investigations that convicted him as the perpetrator. He overpowers Inspector Lucas while jogging and kidnaps her. It quickly becomes clear that Stach isn't out for revenge, but rather to convince Lucas that he was the victim of a miscarriage of justice. Despite the danger she is in, Ellen tries not to be intimidated by Stach and listens to his arguments. When Ellen's colleagues find her and free her, Stach escapes at the last moment. The encounter with Stach left its mark on the inspector.
In addition to the search for Stach, she takes up the old investigations again – despite the skepticism of Chief Inspector Boris Noethen. The main witness for the prosecution, Marie Heusler, who claims to have observed Stach during a party with the victim, is still absolutely sure of her case. Niklas Brettling, whose testimony incriminated Stach, is also interrogated again. Bernd Stach is arrested while trying to assure his little daughter of his innocence. Ellen now has serious doubts about his conviction and continues to press ahead with the investigation. She is amazed that Marie's testimony in court a year ago was not more questioned. Lucas' path leads to Prof.
Kellermann, highly decorated psychology professor and court expert who examined Marie Heusler's testimony in court and still considers her testimony to be credible. Lucas initiates a new crime scene inspection with all witnesses - which makes Marie Heusler very insecure. In addition, Niklas Brettling does not appear for the crime scene inspection. Chief inspector Tom Brauer researches Niklas' background and learns that the orphan Brettling was supported during his time in the children's home by an organization whose board is Kellermann. Marie breaks down shortly thereafter and confesses in conversation with Lucas that Professor Kellermann should never have acted as an expert: The unstable Marie was already in therapy with Professor Kellermann before she testified against Stach.
Inspector Lucas has far-reaching suspicions and is researching on thin ice with Chief Inspector Judith Marlow: Is it possible to manipulate witness statements? And if so, who would benefit from it? Lucas' courageous path takes her deep into the psycho-systemic structure and thus directly to the perpetrator.