So Young, So Bad (1950)

Idealistic and naive Dr. Jason arrives at a school for delinquent girls and immediately begins to try to make a difference in the lives of some of the inmates. Oblivious to the sadistic treatment of the girls by the matrons, it takes a rebellious girl named Loretta to open his eyes. Assisted by a female staff member, Jason finally gets proof of the abuse and threatens the head of the school with exposure unless he is given free rein to run things.