Young Warriors (1983)

A young woman is gang raped and murdered in a California college town, sparking her brother Kevin to take up arms by night with a gang of like-minded vigilantes from his fraternity, brutally punishing any miscreants they catch in a criminal act. In the meantime, Kevin debates the issue of violent crime in the U.S. with his teachers and others during the day. As Kevin and his gang head toward a final, bloody confrontation with the low-lifes who murdered his sister, other scenes show the difference between his character, now violent, and the normal people he is supposedly protecting.