Park Plaza Mall has just installed a state-of-the-art security system, which includes security shutters across all exits, and three high-tech security robots, programmed to disable (using tasers and tranquilliser guns) and apprehend would-be thieves. Four couples (Married pair Rick and Linda, Greg and Suzie, Mike and Leslie, and Ferdy and Allison) decide to have a party in one of the furniture stores where three of them work. They all stay after hours at the mall, drinking, partying, and eventually three of the couples have sex in the furniture store beds, while the fourth couple, Alison and Ferdy, who were introduced by Greg and Suzie, watch old science fiction films on TV.Outside, a lightning storm strikes the mall several times and damages the computer controlling the security robots, which kill their technicians and a janitor, before going on regular patrol in the now empty mall. Two of the teens (Mike and Leslie) leave the furniture store to buy cigarettes, and are subsequently killed by the robots - now the "killbots" of the movies original title. The surviving teens witness the killbots kill Leslie, and the men and women are forced to separate, the men into the mall and the women into the air ducts, when the killbots begin their attack.The men break into a sporting goods store ("Peckinpah's") to arm themselves with guns, whilst the girls take gas and flares from an automotive store after Suzie has a panic attack and leaves the air ducts to help Greg, with Allison and Linda following her, not wanting to leave her in the mall alone.Utilizing a propane tank, Rick, Greg, and Ferdy blow-up and appear to destroy one of the killbots (Though it later recovers). Rick, Greg and Ferdy then rig the mall elevator with a booby trap. A second killbot ambushes the women while the men finish rigging the elevator, and Suzie's screams alert the men that the women are in trouble. They rush to help, but are too late. Suzie is killed as the killbot utilizes its laser, setting fire to her gas can and setting her aflame, while Greg watches in horror. He tries unsuccessfully to shoot the killbot, before Rick drags him away.The teens, now regrouped, are able to destroy a killbot by luring it into the booby-trapped elevator. They then hide out in the restaurant where Allison works. Greg confronts Allison and Linda about leaving the air ducts, which led to Suzie's death. Greg also exhibits signs that he's beginning to crack. The girls try to explain, but Greg has difficulty accepting their explanation, going so far as to pull his gun on Ferdy when he intercedes on Allison and Linda's behalf. Rick manages to calm him down, and Ferdy suggests destroying the main control centre for the killbots, thinking that it will shut them down. Greg and the others support the idea. They begin to make their way to level 3 of the mall where the killbots' control centre is located.Greg, continuing to behave recklessly over Suzie, and despite the others trying to get him under control, gets too far ahead of them and is killed when one of the remaining killbots ambushes him and throws him over the balcony, where he falls to his death three floors below. While on the run, the remaining teens see the killbot that was believed to be destroyed and realize there are still two left to deal with. The final four, Allison, Ferdy, Rick, and Linda take refuge in a department store as the remaining two killbots work to gain access.Hearing one of the killbots gain entrance in the store's lower level, The group sets up store dummies and mirrors in an attempt to confuse the killbot waiting outside the upper-level door, then open it up. The plan works, and when the killbot starts firing at the dummies, one of its lasers reflects back off of a mirror, hitting the killbot and setting it firing blindly. Linda is killed when one of the lasers hits her, and Rick, enraged, drives a store golfcart into the killbot, firing wildly. He is electrocuted by a bolt of electricity, but his actions finally destroy the second killbot completely.Their deaths leave Alison and Ferdy as the only two survivors to search for the control centre in the storage areas of the mall. The third and final killbot corners Alison who is rescued when Ferdy shoots it point blank, damaging its laser, and setting himself up as a target instead - the killbot strikes and appears to kill him as Alison escapes. Alison falls to the lower mall injuring her leg, and sets another trap for the killbot in a paint store, by mixing paint and chemicals from the shelves. She goads the killbot into the store where it becomes stuck - its tracks unable to find traction on the spilled paint and thinners - and throws the flare into the store where the volatile chemicals explode, destroying the final killbot. As she leaves the store, she hears Ferdy call her from the upper mall, revealing that he was still alive. The film ends with Alison and Ferdy together as the mall is now at daytime, showing that Alison and Ferdy survived the night massacre.After the credits roll, a killbot shows and says "Thank you, have a nice day" as then it cuts to black