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 keeps secret of how they taunted Robin - backed her into a corner until, frightened, she stood on a window ledge - and fell to her death. Though an accident, the then-12-year-olds feared they would be held responsible and vowed never to tell. But someone else was there that day - watching, and now, that someone is ready to exact murderous revenge on prom night.