Plot
On December 12, 2019, nearly five years after the events of My Heart is a Chainsaw, 22 year old Jennifer “Jade” Daniels is released from prison and returns to her hometown of Proofrock, Idaho. Jade was arrested because she was captured on video killing her father, but was not convicted of his murder because his body was never found. Additionally, Sheriff Hardy's testimony pointed to her innocence. Jade first meets with Hardy at the dam. He shows her a white elk he has observed; the elk is walking on the frozen lake and later wanders around downtown Proofrock, seemingly lost. Junior deputy Banner Tompkins drives Hardy and Jade back to town. Tompkins is now married to Letha Mondragon; together, they have a 2-year-old daughter named Adrienne. Letha, who was severely injured when the ghost of Stacy Graves tried to rip off her jaw, has spent the intervening years becoming an expert in slasher movies like Jade, believing that she could have saved the massacre victims if she had been more aware of the supernatural threat.
Meanwhile, convicted serial killer Dark Mill South is being transported through the area under armed guard in order to lead authorities to the bodies of some of his victims. A previous confrontation with one of his victims left him with a missing hand, which he has replaced with a hook. A blizzard covers the Proofrock area, making travel and communication difficult for the rest of the novel. An avalanche strikes the prisoner convey, killing most of the police officers. Dark Mill South escapes.
A Proofrock high school student, Toby Manx, is lured out of a motel where he was having a tryst with classmate Gwen Stapleton. Once outside, he is eviscerated and dies in the motel parking lot. Cinnamon Baker, a survivor of the previous massacre and now a high school senior, calls 911 and speaks with Banner and Jade. She claims that Toby was killed after they had met for sex in a car. [lower-alpha 1] Cinnamon also claims to have found Gwen disemboweled and hanging from a tree. She claims that she saw someone matching Dark Mill South’s description committing the murders. Jade notes that the deaths sound similar to the opening scenes of the slasher movie Scream . Cinnamon is taken to the police station for her safety, but is not locked in a cell.
The next day, Jade is picked up by Letha and taken to the police station. Banner has not heard from the other police officers, and no one in town is aware of the avalanche. The three discover that Cinnamon has escaped. Banner and Jade follow her footprints to a nearby retirement home.
Cinnamon’s twin sister Ginger is a patient at the retirement home. During the yacht massacre that took place during Chainsaw, Ginger was left behind alone on the yacht while a construction worker rescued Cinnamon and Galatea Pangborne. Ginger escaped the yacht and survived in the woods for several weeks. Ginger and Cinnamon are identical twins, but Ginger’s head is kept shaved so she doesn’t try to pull out her hair.
Banner leaves Jade at the retirement home and returns to the station. Jade sneaks into Ginger’s room speak with her. Ginger claims that she and her sister once found a blob of organic tissue under the town pier. After Ginger was locked up at the retirement home, Cinnamon apparently saw the blob grow into a young girl and disappear. Jade is unsure whether or not to believe this story.
Jade later stumbles onto the bodies of two high school volunteers, who have been stabbed to death after sneaking off to an empty room to have sex. Jade notices that these murders are similar to the deaths of two characters in another slasher film, Friday the 13th . Deciding she needs to return to the police station to warn Banner about the killings, she discovers the body of another teen employee, who was suffocated when a garment bag was placed over his head. Jade notes this death is similar to a death in the movie Black Christmas . She uses the teen’s snowmobile to return to the police station.
Concurrently, three students (Abby, Wynona, and Jensen) sneak into the high school to play a game of strip basketball. Wynona is attacked and killed with a heavy trophy, and Abby is attacked with the lid of a toilet tank. Jensen is impaled on the antlers of a mounted elk head (resembling a death in Silent Night, Deadly Night ). Abby is able to call the police station, but later dies of her injuries.
Meanwhile, Letha, alone with her daughter at the station, sees a figure outside and shoots birdshot at him, believing it to be Dark Mill South. She actually shoots Rexall, the school janitor. Rexall, in pain but not severely hurt, lashes out at Banner and Lonnie (the town mechanic) when they try to help him. Banner places Rexall in a holding cell.
Jade believes that the blob the twins found under the pier may have been a reanimated Stacy Graves, so Letha and Jade take a snowmobile across the frozen lake to investigate Terra Nova. While there, Jade and Letha bond over their situation and their shared love of slasher movies. Jade also points out to Letha that many of the deaths resemble deaths from slasher movies. Jade and Letha stumble across Dark Mill South, who has been hiding in one of the abandoned homes. South’s internal monologue reveals that he has been hiding at Terra Nova the entire time since his escape, and therefore he could not have been involved in the recent murders.
Letha injures South by throwing knives at him. He quickly recovers and throws one of the knives back at her, injuring her shoulder. Letha leads South away by running to another house. Jade follows and attacks South from behind with a hammer, causing him to fall through rotting floorboards of the house to the basement. This slows South down slightly, but injures Letha further when the house collapses. The two women lose the snowmobile key in the struggle, and are forced to walk back across the lake. On the way they meet Claude Armitage, the high school history teacher. Armitage’s internal monologue reveals that he had an illicit sexual relationship with Cinnamon Baker. He is also implied to be grooming Galatea, who is only 14. Upon returning to the shore of the town, Armitage, Jade and Letha discover the mutilated body of Lonnie. Lonnie’s murder resembles the opening scene from It Follows. They also find the snowmobile, meaning Dark Mill South found the key and is already in Proofrock. The trio return to the police station. Letha passes out from her injuries. Hardy and Cinnamon also arrive at the police station.
Prior to arriving at the police station, Cinnamon has driven to Main Street using Banner’s truck. She warns eight of her high school classmates to lock themselves in the video store for their own safety. At the station, Cinnamon explains that she lied to Ginger about feeding the blob so her twin would continue talking to her. Ginger wanted the blob to kill Proofrock residents and for the murders to be blamed on Jade. Since most of Terra Nova died and very few Proofrock residents died, Ginger feels the need to "even the score". After this however, “Cinnamon’s” wig falls off, and she is revealed to be a disguised Ginger, who runs away.
Jade and Armitage leave the station. Jade plans to get the town doctor to help Letha. Armitage goes to the retirement home to see if the real Cinnamon is still there. Jade passes through Main Street and sees Banner’s truck, left unlocked and running. She finds one of the twins murdered beside the truck. Jade believes the dead twin is Cinnamon and that she has been killed by Ginger.
The truck is next to the video store. Jade sees a body in the video store window and goes inside. Most of the teens are dead. They were given poisoned cupcakes by one of the twins, a reference to the film Happy Death Day. After they died, Dark Mill South entered the store and began mutilating their bodies. Jade believes it was South who killed the twin outside, and since she has not seen Happy Death Day, which came out when she was in jail, she believes South killed all the teens. Two of the eight teens survive the encounter because they didn't eat the cupcakes. Jade and the surviving teens try to fight Dark Mill South. Jade escapes onto the street. South follows, and the living twin (who Jade believes is Cinnamon) arrives and confronts South, claiming that he killed her sister.
South is slowed by Cinnamon, but he turns to attack Jade. Kimmy Daniels, Jade’s absentee mother who was working at the dollar store nearby, attacks South with her purse, distracting him momentarily. Suddenly, Kimmy is killed by the white elk, which is still wandering Main Street. The white elk, which is implied to be the blob that Ginger and Cinnamon found under the pier, is a manifestation of the vengeful spirit of Melanie Hardy, sheriff Hardy’s daughter who drowned nearly 30 years prior while swimming with her friends. The elk only attacks the people who were with Melanie when she died. It was therefore the elk that killed Lonnie; the elk leaves after killing Kimmy.
Cinnamon tries to attack South again, but he throws her into the truck’s bumper. Cinnamon is badly injured, but lives. It is revealed that both twins had shaved their heads and were wearing wigs. It is implied that Cinnamon was the one committing the murders, in retaliation for her classmates spreading rumours about her relationship with Armitage. Jade also believes that Cinnamon killed her sister. Jade believes that Cinnamon planned the murders to resemble slasher movies in order to frame Jade, but later decided Dark Mill South was a more believable scapegoat.
Before South can recover and attack Jade again, Banner hits South with a snowplow and drives it into the lake. The town's historic pier is destroyed as it can't hold the weight of the plow. South climbs out of the lake. Jade stabs South in the heart, finally killing him.
After South’s death, Jade and Hardy sit outside. Rexall is sent to bring them inside. The white elk arrives; it tries and fails to gore Rexall. Rexall shoots the elk, which dissolves. Inside it is a version of Melanie Hardy, who is also slowly dissolving. Jade and Hardy walk across the lake in order to return her spirit to the lake. It is implied that Hardy decides to drown so he can reunite with his daughter's spirit.
When the authorities arrive, Jade takes responsibility for driving the snowplow into the lake so Banner doesn’t lose his job, both out of friendship and because she believes Banner can better protect the town from future threats. Jade is arrested, since destroying public property violates her parole. Before being taken away by police helicopter, Jade holds Dark Mill South’s hook hand up in triumph. Galatea blackmails Armitage into leaving town, leaving him a picture of Jade's arrest as a memento.
