On Prom Night, a young couple by the name of Brad and Lisa sneak away from the dance to have sex in Brad's car. They are distraced when candles appear on the car hood. Brad climbs out and is stabbed with a metal crucifix. The killer then slashes Lisa's throat and burns the car. The killer is apprehended by Father Collins, and is revealed to be the religious fanatic Father Jonas. Jonas is transported to another church, were he is kept sedated in the church tower to avoid a scandal.
Some years later, Collins informs a young priest named Davis that his missionary trip to Africa has been postponed. Feeling poorly, Collins goes home, leaving Davis alone in the tower. He fails to drug Jonas again, allowing the homicidal priest to escape. He garrots the young priest throws him from the tower before escaping. Collins learns of the death and Jonas' escape and finds that he is headed for his old church grounds, which have since been closed down.
Meanwhile, two young couples, Mark, Megan, Laura and Jeff, decide to spend their graduation at the abandoned church grounds rather than attend prom. Mark's troublesome younger brother Johnathan follows them and secretly films Jeff and Laura having sex, only to be attacked by Jonas, who murders him. Jonas retrieves his old metal crucifix while Megan falls in the cellar, injuring herself. Mark goes to get a first aid kit, but while he is away, Megan receives an obscene phone call from Jonas. Jonas uses his old lair to gain entry to the house and makes his way to Laura's room. Jeff goes to search for her in the attic, but only finds Jonas wearing her hair. He is then killed by Jonas.
Megan and Mark stumble upon Jonas' lair and then witness Jonas setting Jeff and Laura's crucified bodies alight. Mark flees to the roof, but Jonas stabs through the roof with the crucifix, causing Mark to while as Megan watches. Jonas makes his way outside and stabs Mark in the chest. Megan is chased by Jonas throughout the building, but in finally cornered. Suddenly, Collins appears and shoots Jonas. As he tries to comfort Megan, a wounded Jonas appears and throws his crucifix at the old priest, killing him.
Megan flees to the shed outside and beats Jonas down with a shovel. As she begins to pray for forgiveness, Jonas sets the shed on fire and attacks her. During the struggle, Jonas falls onto the spikes of some farm machinery and is impaled. Megan runs outside and locks the door, finally killing Jonas as the shed explodes. As the film ends Megan is shown being placed in an ambulance.
- Brad - Stabbed with a metal crucifix.
- Lisa - Throat slashed with metal crucifix.
- Father Davis - Garroted and thrown from church tower.
- Johnathan - Killed offscreen, possibly stabbed or strangled.
- Laura - Stabbed to death offscreen and scalped with metal crucifix.
- Jeff - Head crushed by Jonas' bare hands.
- Mark - Stabbed in the hand, falls from roof and is then stabbed in the chest with metal crucifix.
- Father Collins - Metal crucifix thrown into neck by Jonas.
- Father Jonas - Shot, struck on the head with a shovel, impaled on farm machinery spikes, stabbed in the chest with a trowel and blown up.