A supermarket closes and the night crew begin restocking for the next day. Craig – the ex-boyfriend of cashier Jennifer, Elizabeth Cox – appears and the two quarrel. Worried about her friend, Linda, Renée Estevez – witnesses the debacle and presses her security button at her cash checkout. Co-owner Bill, Dan Hicks, shows up and a fight ensues. Craig escapes onto the shop floor.
The owners gather the night crew to announce that they are selling the store, and that the staff will soon lose their jobs. The employees are assigned to mark down all the stock in preparation for the close. Craig makes telephone calls to the store, upsetting Jennifer. The police arrive but do little to help and just tell the group to be careful.
After finishing her shift, Linda is stabbed by an unseen assailant. Bill spots someone trying to enter through the back door and goes outside to investigate. He finds Craig watching Jennifer through the bathroom window and is rendered unconscious.
Back in the store, the killer begins to brutally murder the employees and scatters their severed body parts around the store. Noticing that everyone seems to have vanished, Jennifer investigates and discovers several bodies and body parts in the storerooms. Terrified, she is attacked by the killer but manages to escape back to the shop floor. Hearing someone at the door, she tries to draw their attention, but the person has left by the time she gets there. Craig grabs her, but she beats him with a meat hook.
Bill then staggers in. Claiming that Craig attacked him outside the store, he proceeds to call the police. Jennifer notices Bill's hands are covered in blood and realizes that he is the killer. Bill tells her that he cannot let his partner sell the store, so he killed him and got carried away, killing everyone. Bill attacks Jennifer and chases her around the locked building. A delivery man appears outside, but Bill kills him before Jennifer can get his attention. Bill re-enters the building and stalks Jennifer again. Craig tells Jennifer he saw Bill killing Linda, and that he climbed into the building through the bathroom window to save her. Bill appears and bludgeons Craig while Jennifer flees.
Crawling out the bathroom window, she tries to escape in her car but finds Linda's body inside. Bill grabs her legs and pulls Jennifer under the car, but she stabs him with a knife. She heads to a phone booth to call the police, but Bill reappears and starts to smash the booth to get at her. He topples the phone booth over and traps her, but Craig appears and brutally damages him with a meat cleaver.
When the police arrive, one of the policemen finds the carnage in the store. The severely injured Bill claims that Jennifer and Craig are responsible for the attack. The policemen ignore their protests and arrest them. Bill suddenly opens his eyes as Jennifer screams, leaving all of their fates unknown.
