The Edukators

Set in 2004, the film revolves around three young anti-capitalist activists in Berlin's city centre: Jule (Julia Jentsch), her boyfriend Peter (Stipe Erceg) and his best friend Jan (Daniel BrÃ¼hl). Jule is a waitress struggling to pay off a â¬100,000 debt she incurred a year ago when she crashed into a Mercedes-Benz S-Class belonging to a wealthy businessman named Hardenberg (Burghart KlauÃner). After her eviction for non-payment of rent she moves in with Peter and Jan, who are often out all night. While Peter is in Barcelona, Jan tells Jule that he and Peter spend their nights "educating" upper-class people by breaking into their houses, moving furniture around and leaving notes saying "die fetten Jahre sind vorbei" ("the days of plenty are over") or "Sie haben zu viel Geld" ("you have too much money").
After hearing this, Jule convinces the reluctant Jan to break into Hardenberg's home in the affluent Berlin suburb of Zehlendorf while he is away on business. During the break-in, the thrill of the moment entices them to kiss before Jan leaves Jule alone for a few minutes; he does not want to destroy his friendship with Peter. As she wanders around outside Jule accidentally sets off the house's floodlights, and they quickly leave.
When Peter returns the next day, Jan and Jule do not tell him about their activities the night before. Jule realises that her mobile phone is gone, and she and Jan leave later that night to look for it in the house. After she finds it, Hardenberg walks in the door and struggles with Jule when he recognises her. Hearing them, Jan comes downstairs and knocks Hardenberg unconscious with a flashlight. Not knowing what to do, they call Peter and he comes to their aid.
The three cannot decide what to do with Hardenberg and take him to a remote, rarely used cabin belonging to Jule's uncle in the Tyrolean Austrian Alps near Jenbach, overlooking Achensee. As they try to decide how to deal with their hostage, they learn that Hardenberg was a radical himself during the 1960s. A leader of the Socialist German Student Union, he was a good friend of Rudi Dutschke before marrying, getting a good job and abandoning his ideals.
As the story progresses, political ideology and the characters' relationships become the main issues. Peter and Jan temporarily fall out over Jan's developing romance with Jule, and Hardenberg seems to regain some of his former self.
The trio finally decide that kidnapping Hardenberg was wrong and take him back to his house to let him go. As they prepare to leave, Hardenberg gives Jule a letter forgiving her debt and promising not to involve the police. The film ends with Peter, Jan and Jule asleep in the same bed as a group of heavily armed police (Spezialeinsatzkommando)[note 3] gather outside their flat and knock on the door. Jule wakes up when she hears a knock, and the police force their way into the almost-empty flat. Apparently in Barcelona, Jule opens the door to a hotel maid who wishes to clean their room. In the Berlin apartment, the police find a note: "Manche Menschen Ã¤ndern sich nie" ("some people never change"). In the original German version, the Edukators set off in Hardenberg's boat in the Mediterranean, presumably to disrupt the island signal towers supplying most television programming to Western Europe.[note 4]

Question: who was a radical during the 1960s?
Answer: Hardenberg.