Cage Without a Key (1975)

New high school graduate Valerie is on a road trip with a friend when the car breaks down. Buddy, a casual male friend of Valerie's companion pulls over and offers a ride to the girls. Valerie reluctantly decides to take Buddy up on his offer and goes with him while her friend rides with the tow truck driver back to town. Valerie gets very uncomfortable with Buddy's attempts to come on to her and wants him to let her out by the road. He convinces her to stay and drives to a liquor store. He forces Valerie inside after showing her a gun and robs the store, shooting 2 people and killing one. The police come and arrest Valerie and Buddy shortly after. Valerie is charged with murder and convicted despite testimony from her friend and her public defender's help. Sentenced to a tough reform school, Valerie must find a way to survive.