The movie reveals there are two masked killers targeting the prom queen candidates. One of the killers is Tiffany Falconer, the popular girl and queen bee, who is revealed during the prom night chaos. The motives are tied to personal grudges and the dark history surrounding the characters, including Lori's family background and the town's troubled reputation.

The movie reveals that there are actually two masked assailants killing the prom queen candidates, with one of them ultimately revealed to be Tiffany, the popular girl and queen bee of the 'Wolfpack' group at Shadyside High.

Lori and Megan start as best friends, but their relationship becomes strained after Megan stages a prank that causes a rift between them. Megan suspects a serial killer is targeting the prom candidates and tries to warn Lori, but Lori rejects her theory, leading to distance between them. They later fight off one of the killers together before escaping.

The prom queen competition is central to the plot, with Lori running against Tiffany and her friends. The competition creates tension and rivalry, culminating in a dance-off where Lori wins over the crowd and Tiffany is embarrassed. Lori is eventually named prom queen, which triggers a chaotic killing spree by the masked assailant(s).

Several prom queen candidates and their partners are killed in various brutal ways: Christy Renault is stabbed the night before prom; Linda and her boyfriend are mutilated in a classroom; Debbie and her boyfriend Judd are killed in the basement power room; Melissa is killed in the girls' changing room. These killings reveal the presence of two killers.

Lori is an outcast at school due to rumors that her mother murdered her father, though she was deemed innocent. This personal trauma is a subplot that influences her character and the way other students treat her. Tiffany harasses Lori about her mother's past, adding to the tension. The subplot is connected to the killer's motives but is not deeply explored.