Prom Night (1980)

For six long years, Hamilton High School seniors Kelly Lynch, Jude Cunningham, Wendy Richards, and Nick McBride have been hiding the truth of what happened to 10-year-old Robin Hammond the day her broken body was discovered near an abandoned convent. The foursome keep secret how they backed Robin into a corner until, frightened, she stood on a window ledge and fell to her death. Though it was an accident, the then-12-year-olds feared they would be held responsible and vowed to never tell. But someone else was there that day--watching--and that someone is now ready to exact murderous revenge on prom night.