Plot
Judith Myers (Bryce Dallas Howard) is at home alone on Halloween Night. Her younger brother Michael (Ty Simpkins) has just gone out trick or treating. Judith's boyfriend Steve Haley (Jai Courtney) arrives and they go upstairs to took Unknown to them, an unseen person comes in through the back door and takes a large knife from the kitchen. Steve comes downstairs to make himself a sandwich, oblivious to the person sneaking up behind him. The intruder then caves his head in with a baseball bat.
The killer goes upstairs, where a naked Judith is sitting in front of her vanity mirror. She looks up and catches the figure in the reflection; she is horrified to recognizse them as Michael, wearing his Halloween mask. She tries to cover herself up and yells at Michael, who then reveals the knife in his hand and he viciously stabs her to death. Michael then exits through the front door and is found crossing the lawn by his parents (Steve Buscemi and Julie Benz).
Fifteen years later, Michael (Tom Hardy) has been locked away in Smith's Grove Sanitarium. He is finally due to stand trial for his brutal crimes and is being transferred from Smith's Grove. However, he breaks free of his chains and escapes, murdering the security detail while doing so.
Dr Sam Loomis (Idris Elba), the child psychologist who took Michael's case, is informed of Michael's escape. He buys a gun and heads for Haddonfield, believing that Michael will be there. Michael, meanwhile, arrives at a truck stop where he violently murders a mechanic and takes his overalls.
In Haddonfield we meet Laurie Strode (Emma Stone) and her friends Annie Brackett (Lyndsy Fonseca) and Lynda Van Der Klok (Amanda Seyfried) on Halloween. For that night, both Annie and Laurie have baysitting jobs; Laurie is watching Tommy Doyle (Bradley Steven Perry) and Annie is looking after Lindsay Wallace (Bella Thorne). Annie, however, wants Laurie to watch Lindsay as well so that Annie can have sex with her boyfriend, Ben Tramer (Aaron Paul).
Sheriff Tom Brackett (Bryan Cranston) arrives at the local cemetery to investigate the scene of a murder. The graveyard caretaker has been found dead and one of the tombstones stolen. Also present at the scene is Dr Loomis, who explains to Brackett that Michael has escaped and that he has most likely commited the killing. The two investigate and learn that the headstone was taken from Judith Myers' grave.
That night, Annie rings Laurie and persuades her to let her drop off Lindsay. Returning home, she rings Ben and tells him to come over. While doing so, however, she accidentally spills butter on herself and goes to get changed. She hears noises outside and leans out of the window to investigate, assuming that it's Paul. Michael suddenly appears and drags her through the window. Ben arrives and looks through the house for Annie, but finds her nowhere. He gets pissed and decides to leave. However, Michael appears in the backseat of his car and kills him.
With the Wallace house now empty, Lynda and her boyfriend Paul Freeman (Henry Cavill) arrive to drop in on Annie, but are delighted to find themselves alone. They ring Laurie, who explains that she is watching both kids and Annie is probably at Paul's, meaning they have the house to themselves. They go upstairs and have sex. Afterwards, Lynda sends Paul downstairs to get her a beer. In the kitchen, Paul is attacked by Michael and stabbed. Michael then uses a white sheet and Paul's glasses to disguise himself, fooling Lynda into thinking that he is Paul. She quickly becomes irritated when he doesn't speak and fails to produce a beer. She gets out of bed to ring Laurie, but Michael walks up behind her and strangles her to death.
At the Doyle house, Laurie puts the children to bed and decides to go for a walk, strolling over to the Wallace house. She notices that all the lights are out so takes a look around the house. She goes upstairs and finds Annie's body on the bed with Judith's headstone above her. Laurie is horrified and subsequently stumbles upon the bodies of the others. As she walks out into the hallway, Michael emerges from the shadows and slashes her arm, knocking her over the rail and onto the stairs. She manages to limp back to the Doyle house, where she wakes Tommy up and he lets her in just in time. Laurie orders him to lock himself and Lindsay in the upstairs bedroom to keep themselves safe. As he runs upstairs, Michael crashes through the window. but Laurie manages to subdue him by jamming a knitting needle into his neck.
Laurie goes upstairs and alerts Tommy and Lindsay that the danger is over. Tommy then notices Michael coming up the stairs. Laurie locks them into the on suite and then hides in the closet. Michael follows her and tears through the door, but Laurie temporarily blinds him by jabbing a coat hanger in his eye. She then picks up his knife and slashes him with it, incapacitating him. Laurie instructs Tommy and Lindsay to run down the road to a neighbor's house to call the police. On their way, they are spotted by Loomis, who makes his way to the Doyle house.
Michael, meanwhile, wakes up and attacks Laurie once again, causing both of them to fall down the stairs. he jumped on top of her and Begins the Strangle her Loomis arrives and shoots Michael, who drags Laurie across the floor. Michael grabs a knife and stabs Loomis in the leg. Loomis, although now stuck on the floor due to his injury, manages to retrieve his gun and shoot Michael again. Laurie then grabs Michael's knife and stabs him the chest, shoving him away and sending him crashing through the door, his body falling into the swimming pool. Laurie runs to Loomis' side, but he end up consoling her instead. She helps him to his feet and then sits down at the table, softly weeping. Loomis walks outside and is shocked to find the pool empty, Michael's body gone.