Berlin, April 1929: Cologne police lieutenant Gereon Rath (Volker Bruch) joins his colleague Bruno Wolter (Peter Kurth) in the investigation against a porn ring in Berlin. After a raid his case turns into a new direction after stumbling over a photograph. He meets the stenographer Charlotte Ritter (Liv Lisa Fries) who feeds her family with work for the police. In a heist on a freight train russian revolutionaries append a wagon with explosive content to be smuggled to Berlin.

Rath attempts to interrogate Konig further about the missing film reel, and the Russian revolutionaries' location is revealed by an informant.

Kardakov flees after the Soviet attack on The Red Fortress. Rath receives an uninvited guest in his apartment.

The May Day stand-off between communist protesters and police erupts in bloody violence.

As Berlin becomes increasingly politically charged, those in charge look to change the discourse on the May Day violence.

Kardakov seeks help in retrieving the Sorokins' gold. Rath faces a moral dilemma, and Bruno makes a power play.

Lotte's private investigation leads her to the depot where the hijacked train is held. Rath relives painful memories of the front.

Rath and Bruno finally get a lead to the location of the missing film reel, but after the truth come the consequences.