Pilvilinna (1970)

Teenager Erik returns from Paris to Finland in a rowboat and is accosted by a gang of youths in the countryside. He walks to Helsinki, returns to his parents' home and his old high school filled with angry radical teens who, typically for the era, consider the teacher-imposed discipline as another form of capitalist imperialism. Almost reluctantly Erik drifts together with Annika, a girl from a wealthy family, and starts experimenting with sex and marijuana. In the same nonchalant manner Erik gets involved in demonstrations and school politics which escalate into a violent school strike leading to police intervention and heavy sanctions.

Unfortunately the movie Pilvilinna is not yet available on HBO Max.