Benton, NY - Halloween 2015 - Wearing a jack-o-lantern mask, 18-year-old Patrick 'Trick' Weaver suddenly murders several high school classmates at a costume party. Cheryl Winston, who is hosting the party, stops Trick by stabbing him in his stomach with a fireplace poker. With Cheryl in shock, football team captain Troy Meeks takes credit for taking down Trick. Cheryl's friend Nicky Taylor survives Trick's stabbing.Sheriff Lisa Jayne and Detective Mike Denver begin investigating the case at the hospital, where Dr. Steven treats Trick. Trick gets free of his cuffs, attacks Mike, and kills multiple staff members while attempting to escape. Mike and Lisa shoot Trick several times after he takes Cheryl hostage. Trick falls through a window to the ground below. When Mike and Lisa make it outside, they find Trick missing. EMT Len tells Mike and Lisa that he swerved his ambulance to avoid Trick.Mike and Lisa's subsequent investigation reveals no one knew Trick's true identity or address. Mike believes Trick survived, possibly through supernatural means, but Lisa closes the case by concluding Trick probably drowned in the Hudson River.Riverton, NY - Halloween 2016 - Someone wearing a white demon mask kills multiple people at another costume party. Mike tells Lisa he believes Trick has resurfaced.Hudson Village, NY - Halloween 2017 - Trick's cult following continues to grow when more murders are committed with his m.o.Shady Creek, NY - October 30th 2018 - At a bar, Mike tells fellow FBI agents Sam Swift and Christina Mendez that he believes Trick is moving his murders further down the river every year. Due to the different DNA found on each mask worn by the murderer, bartender Brooke suggests a copycat may be responsible.Trick captures Swift in the bar's bathroom and decapitates him outside with an elaborate trap. Trick also kills Mendez, which results in Mike being fired from the FBI.Benton, NY - October 30th 2019 - Lisa summons Mike to a crime scene when deputies Wan, Slater, Green, and Iris Reddick discover Mike's name written in blood as an apparent taunt.Cheryl goes to the hospital to visit her bedridden father, who mysteriously fell from a factory roof. Cheryl's father sees an ominous face appear on his room's TV, but he is unable to communicate with Cheryl or Dr. Steven.Mike chases Trick through a cemetery, but Trick gets away. Trick lures Deputy Green to a barge where he impales her with a trap before decapitating her with Agent Mendez's tombstone.Mike and Lisa investigate Cheryl's former house where the 2015 party took place. They find evidence that Trick was there. Someone steals Mike's SUV while he and Lisa are inside.Cheryl and Nicky take Nicky's younger siblings Janice and Greg to a church fundraiser where diner owner Mr. Talbott entertains locals with a horror movie marathon inside and a haunted maze outside. Troy Meeks sneaks into the event with Smooth Jonny and several other buddies, although Talbott catches them.Deputy Reddick reports finding Mike's stolen SUV outside the church. Mike and Lisa race to the event and find Reddick dead.Wearing skull makeup and a black hoodie, Trick murders several scare actors in the maze. Trick stabs Nicky. Trick also kills Talbott in the projection booth. As panicked patrons evacuate, Mike rescues Cheryl, Janice, and Greg and sends them to the hospital with Nicky.Mike and Lisa find Troy. Mike and Lisa warn that they believe Trick wants to kill Troy for stabbing Trick with the fireplace poker in 2015. Tory confesses that Cheryl actually stabbed Trick. Mike and Lisa race to the hospital to warn Cheryl.Cheryl visits her father while at the hospital. Surveillance video suddenly plays on the TV revealing Trick caused her father's accident by throwing him from the roof. Cheryl pulls back the bed sheet to discover her father gutted. The hospital's power goes out as Trick attacks Cheryl.Mike and Lisa find Cheryl tied up. Trick viciously stabs Lisa, Mike, and then Cheryl. Following a fight between everyone, Cheryl recovers a gun and shoots Trick several times. Mike then tackles Trick through a window and onto a car in the parking garage beneath them. Mike sees that the murderer is actually Smooth Jonny wearing the skull makeup and hoodie.Len, the EMT from 2015, and Brooke, the bartender from 2018, arrive in skull makeup and hoodies to collect Smooth Jonny while Mike remains helpless from his wounds. Deputy Wan and Deputy Slater also arrive. Slater reveals he too is wearing skull makeup when he shoots Wan. Bound to a wheelchair, the real Patrick Weaver joins the group. Trick explains that he and his accomplices were part of an elaborate plot to create the illusion of a supernatural boogeyman. Slater stabs Mike and leaves him with Trick before exiting with Len and Brooke.Mike manages to pull Trick out of his wheelchair. Cheryl comes to help Mike. Cheryl realizes who Trick really is when she sees the scar from the fireplace poker on his stomach. Cheryl lets Trick go, but follows him back inside where he deletes surveillance footage from the hospital's security system.While Dr. Steven treats Lisa, Slater returns to report what happened in the garage. Lisa notices makeup on Slater's neck.Cheryl confronts Trick. Following a violent fight, Cheryl stabs Trick to death.Cheryl wheels Trick's body into Lisa's room. Cheryl explains that Trick is more than one person. Lisa calls out Slater, who suddenly attacks. Cheryl and Lisa kill Slater together.With plans to expand their plot, Len and Brooke leave town with Dr. Steven, who is also part of their conspiracy. Cheryl and Lisa team up to track them down with Mike, who recovered from his injuries.