The Berlin investigator Jan Koller has to solve an unusual death in his native city of Prague - not as a BKA officer on a foreign assignment, but as the main suspect in a murder. After investigating the death of a colleague, Koller actually wanted to turn his back on unloved Prague as quickly as possible. But then he learns from his colleague Klára Majerova that his father, who was believed to be dead, lives and works in a senior citizens' shared apartment where Germans live. The reunion with his father is unhappy, the trauma of his childhood comes alive again for Koller, his father wants nothing to do with him. But Koller doesn't want to get rid of that easily and stays in the senior citizen's shared apartment overnight. Shortly thereafter, Klára Majerova was called to an unusual death: a resident of the senior citizens' shared flat died in a fall from the first floor. Arriving at the crime scene, Klára has a frightening picture: The unconscious Koller lies on the dead Benno Urban. The residents of the house agree that after a heated argument with Benno Urban, Koller pushed him over the railing of the balustrade. Koller knows one thing for sure: he is not a murderer. But how is he supposed to prove his innocence, especially since he can't remember anything?
—ARD Das Erste