Michael Myers murdered his older sister on Halloween in 1963. Halloween 1978, he escaped from a mental institution, traveled to his hometown of Haddonfield, Illinois, and killed sixteen people while attempting to murder his seventeen-year-old sister, Laurie Strode. Laurie escaped after Michael’s psychiatrist, Dr. Sam Loomis, caused an explosion that injured Loomis and left Michael in a coma. Ten years later, on 30 October 1988, Michael is transferred from a federal facility to a state hospital. Although Loomis is still Michael’s doctor, he is not informed of the transfer. While transporting the seemingly comatose killer, the ambulance attendants mention that Michael has a niece, who is living in his hometown. Upon hearing the news, Michael kills the two attendants and escapes. In Haddonfield, Laurie Strode’s orphaned daughter, Jamie Lloyd, lives with Richard and Darlene Carruthers, their teenaged daughter, Rachel, and a dog named Sunday. On Halloween, they learn that their babysitter is not available that evening. Richard and Darlene must attend a function, and they inform Rachel that she will have to watch Jamie. Rachel is upset that she has to cancel a date with her boyfriend, Brady, but agrees to watch her foster sister. She suggests taking Jamie trick or treating, but the young girl is reluctant. Meanwhile, Loomis arrives at the sanitarium and learns of Michael’s transfer. He declares that Michael is “pure evil” and is furious that he was moved over Halloween. They learn there was an “accident” during the transfer, and Michael’s body has not been found. Loomis believes Michael will return to Haddonfield to murder his niece, and races to stop him. When Loomis stops at a gas station outside Haddonfield, he discovers several dead bodies and sees Michael in the garage. Loomis shoots, but misses. Michael speeds away in a truck, blowing up the gas pumps and Loomis’s car as he escapes. The resulting explosion ignites telephone lines and cuts off long distance telephone service to the town. After school, Jamie decides to go trick or treating. Rachel takes her to the store where Brady works, and while Jamie looks at costumes, Rachel cancels her date with Brady. He is upset, but exchanges a flirtatioius look with co-worker Kelly Meeker, the Sheriff’s teenaged daughter. As Jamie tries on a clown costume and mask, Michael sneaks inside, and steals a rubber mask. Jamie screams, and everyone rushes over, but Michael is gone. Later, after the Carruthers leave for their event, Rachel takes Jamie trick or treating, unaware that Michael is inside Jamie’s bedroom. Loomis reaches town and informs Sheriff Meeker that Michael Myers has returned to kill his niece. The Sheriff is doubtful, but Loomis convinces him. Meeker issues a warning to clear the streets, and leaves with Loomis to search for Jamie. They stop at the Carruthers’ house, let themselves inside, and discover that Michael has murdered the family dog. They leave Deputy Logan to watch the house while they continue to search for Jamie. At a local bar, the television news reports that the Sheriff wants businesses to close and everyone to stay inside. The bartender, Earl, refuses to close without an explanation and telephones the police station, but there is no answer. He and several friends leave to investigate. As Rachel and Jamie trick or treat, they stop at Meeker’s house and discover Brady inside with Kelly Meeker. Brady tries to justify his infidelity, but Rachel is furious. Elsewhere, Michael stops at the town power plant, and tosses a power worker into the transformer, causing an explosion that cuts the town’s electricity. Meeker and Loomis find Rachel and Jamie, and take them to the police station. While the girls wait in the car, Loomis and Meeker discover that Michael has murdered everyone inside. As they leave the station, Earl and his friends arrive, and Loomis reveals that Michael has returned. Meeker is angry that Loomis incited a mob, but Loomis insists Earl’s men may be the town’s only defense. At the Carruthers’ home, Deputy Logan learns of the carnage at the station and agrees to join the Sheriff at Meeker’s house. Logan drives away, unaware that Michael is hiding inside his cruiser. Earl’s gang believe they have found Michael in the park and shoot to kill, only to discover they have shot an innocent man. At Meeker’s home, Brady and Kelly are about to make love when they are interrupted by the arrival of her father with Loomis, Rachel, Jamie, and Deputy Logan. Meeker sends Brady to secure the attic windows while Deputy Logan nails shutters closed. Loomis is certain that Michael will return to the Carruthers’ home to find Jamie, and leaves to confront Michael there. Deputy Logan locks the door and stands guard at the entrance. Meeker contacts state troopers on his shortwave radio and relays the situation. Before leaving, he asks Rachel to monitor the radio and let Deputy Logan know when the state troopers are coming. Meanwhile, Kelly brings coffee to Logan, discovers his dead body, and is attacked by Michael, who impales her on a shotgun. Learning that the state troopers are on their way, Rachel goes to inform Logan, and discovers the dead bodies. She rushes upstairs to warn Jamie and Brady. As the killer approaches, Brady sends Rachel and Jamie to the attic while he confronts Michael. However, Michael kills him and pursues the girls. They escape onto the steep roof where Rachel lowers Jamie to the ground with an electrical cord. Michael stabs Rachel, causing her to falls. Unable to rouse the unconscious Rachel, Jamie runs away screaming as Michael gives chase. Loomis finds Jamie on the street, and they hide in the schoolhouse. As alarms go off, Michael finds them and tosses Loomis through a door. Jamie runs away, but trips on the stairs. Michael grabs her leg and raises his knife, but Rachel arrives, sprays a fire extinguisher at him and escapes with Jamie as Earl’s men arrive outside. She insists it is too dangerous to confront Michael, and they drive away in Earl’s truck, with several of his men standing guard in the rear bed. State troopers meet them on the road, and tell Earl to take the girls to the nearby state police station. As Earl speeds in that direction, Michael crawls from beneath the truck. He kills the men in back, climbs on the roof, and rips Earl’s head apart. Rachel pushes Earl’s corpse from the vehicle, takes the driver’s seat, and swerves to knock Michael off. When she slams on the brakes, Michael flies off the roof and onto the road. As he gets to his feet, she runs him over. Sheriff Meeker and the state police arrive. While Rachel talks to them, Jamie notices Michael’s hand move to grip his knife. She holds his hand as the others warn her to get back. Jamie moves away, and Michael gets to his feet, raising his knife. The officers open fire, and Michael’s bullet-ridden body falls into a deep hole. Meeker and Loomis take the traumatized girls home, and Mrs. Carruthers takes Jamie upstairs for a bath. As her foster mother fills the tub, Jamie puts on her clown mask and grabs a pair of scissors. Hearing screams, the others rush to the stairway and see Jamie covered in blood, looking exactly like a young Michael Myers. Loomis aims to shoot her, but Meeker stops him. Loomis collapses in horror as Jamie raises the bloody scissors.