Four twelve-year-old kids play a game called “Killer is Coming” in an abandoned convent. Wendy, who is “It,” stalks Nick, Kelly and Jude. As Kim Hammond walks by with her younger twin siblings, Robin and Alex, she sees Nick on an outside ledge and waves. However, he signals her to go away. Kim is further frustrated that she forgot a textbook and must return to school. Robin wants to play the game but Alex knows they are not wanted and leaves. When Robin joins the game, the other kids chase her, relentlessly shouting, “Kill,” until she is cornered against a window. Backing away, Robin falls through the window to her death. Nick wants to get help but Wendy forces them to make a pact never to tell. As the four kids race off, a shadow falls over Robin’s body. Someone else is there. Soon after, the police think a sexual predator attacked Robin and arrest a suspect. Six years later, the family visits Robin’s grave on the anniversary of her death. It also happens to be the day of the prom at Alexander Hamilton high school, where Kim and Alex are students, and their father, Mr. Hammond, is the principal. As the three enter the school, they pass Mr. Sykes, the new gardener. The kids think Sykes is strange but Mr. Hammond assures them that he has been checked out. Jude has no date for the prom and receives a strange call asking, “Can you come out to play tonight? See you at the prom.” The caller hangs up and crosses Jude’s name off a list of the four kids involved with Robin’s death. As Jude walks to school, she is picked up by geeky Seymour, nicknamed “Slick.” He asks her to the prom and Jude agrees. The stalker calls Kelly next. She thinks it is her boyfriend, Drew, until Drew sneaks up behind her. Nick and his father, Lieutenant McBride, are leaving when Nick’s phone rings. Thinking it is his ex-girlfriend Wendy, Nick ignores the call and tells his father that Wendy cannot accept that Nick is going to prom with Kim Hammond. At work, McBride reviews Robin Hammond’s file with Dr. Fairchild. The suspect, Leonard Murch, was disfigured in a fiery crash as he tried to escape. According to Fairchild, Murch is a “catatonic schizophrenic” and has been institutionalized for six years. Unfortunately, Murch just escaped from the state hospital, taking a nurse hostage. McBride gets word that the nurse’s body has been found at the abandoned convent where Robin died. The stalker calls Wendy but when she realizes it is not Nick, she immediately hangs up. In the hallway before school, Jude tells Kim about her date with Seymour. Fellow classmate Lou puts the moves on Kim but she finds him repulsive. At the deserted convent, McBride wonders why Murch is back in town, but decides not to arouse the fears of the townspeople. Wendy confronts Kim, saying that Nick might be king of the prom, and Kim the queen, but Nick still belongs to Wendy. In the cafeteria lunch line, Lou, wearing a ski mask, kisses Kim and her brother, Alex, punches him. Lou’s friends attack Alex, and Lou sucker punches him. Lou passes Wendy on his way to the principal’s office, and Wendy asks to meet him later. Mr. Hammond suspends Lou, tosses the ski mask in the trash, and sends Alex to the nurse’s office. That afternoon, Kim and Nick stroll on a nearby cliff overlooking a beach and confess their love for each other. Kim is sad about Robin since this would have been her first prom. Nick almost confesses to aiding in Robin’s death but Kim rushes off. Meanwhile, Wendy conspires with Lou to pull a stunt at the prom. In the girls’ dressing room after gym, Kelly tells Kim she is finally going to let Drew have sex with her at prom. A mirror is smashed in the other room and the girls rush to look outside, but only find Sykes changing a light bulb. In the gymnasium, Wendy and Lou lurk in the background while Nick and Kim rehearse their prom entrances from opposite sides of the stage. Meanwhile, police discover the dead nurse’s car and McBride patrols the high school area. That night, Mr. and Mrs. Hammond chaperone the prom and Alex, who has no date, handles the sound system. Nick escorts Kim, Kelly is with Drew, and Jude arrives with Seymour. Wendy angrily waits for Lou who arrives late and brings two friends. Wendy’s entrance prompts Kim to pull Nick onto the dance floor and they become the center of attention while doing a disco dance. Kelly and Drew sneak off for sex but Kelly is too nervous and Drew leaves in anger. Wearing a ski mask, the killer sneaks up behind Kelly and slices her throat. Nearby, Jude and Seymour have sex in his van. They decide to move outside, but stop when they hear someone. Back in the van, Jude and Seymour are smoking a marijuana cigarette when the van door opens and Jude is knifed. Seymour attempts to drive away but is attacked by the killer, who jumps out of the vehicle just before it speeds over the cliff and explodes. Wendy is fixing her makeup in the girls’ room when the lights suddenly go off. The killer, now wielding an ax, chases Wendy through the school before killing her in the auto shop. McBride is relieved to learn that Murch was arrested in another town. Kim looks for her Dad as Sykes drunkenly enters the prom saying there is a killer on the loose. The police lead Sykes away as Kim and Nick get ready for their royal prom processional. Even though Wendy is not around, Lou and his buddies proceed with their plan. Kim and Nick are handed their crowns and take their places backstage. Lou’s friends knock out Nick, tie him up and hand the crown to Lou, but, as the processional begins, the killer sneaks up behind the “king,” and chops off Lou’s head. Kim rushes to help Nick, but the killer traps the two of them. As the three fight, the killer loses his ax. Kim grabs it and whacks the attacker. He looks at her and Kim suddenly realizes the killer is Alex. He staggers outside and collapses. Kim gently removes the ski mask from her brother’s face as Alex tells her that the four kids killed their sister. Kim is in shock as her brother dies in her arms and prom night ends.