In their new case, the trio Schaller, Neuhauser and Flierl have to solve two murders at once – and at a time when Munich is going crazy: the Oktoberfest is in full swing. A neighbor of Detective Inspector Zangel is found dead in his apartment. The lonely pensioner, Josef Kleint, was beaten to death. A valuable painting that adorned the wall of the victim's apartment becomes the center of a maze of suspects. The trail leads the three detectives to the slain ex-janitor's former workplace: the Munich Academy of Music. In the underground of the Königsplatz, the investigators end up in a murder labyrinth of highly skilled speculators with Nazi tendencies. Janitor Uli Schmidbauer knows about the secrets of the basement and apparently tries to make a profit from it. But the ambitious student Stella Bast is on to him. However, she is not the only one who wants to make money. When a second murder occurs, the circle of suspects quickly expands, and the investigators are faced with an even bigger mystery.