The Last House on the Beach (1978)

Sister Cristina, a devoted nun, oversees a group of teenage girls at a secluded beach house, where they prepare for a production of A Midsummer Night's Dream. Their peaceful retreat turns nightmarish when a trio of violent thugs arrives, subjecting the girls to horrific acts of violence and intimidation. Driven by desperation and rage, Cristina abandons her vows and transforms into a fierce avenger, determined to protect her charges and confront the brutal invaders with unrelenting force. As innocence shatters, a dark quest for justice unfolds along the shore.