Kimmy Daniels, a dollar-store clerk, works alone during the blizzard-induced power outage. The store is sustained by a generator. Kimmy obsessively watches a video of a Queen’s Guard remaining motionless despite tourist harassment, aspiring to that stoicism. Her common-law husband Phil recently discovered Indigenous ancestry and insists on being called Holy Crow. Among unsold Christmas items, Kimmy found a small nutcracker soldier she keeps at her register as a symbol of immobility.

Jennifer, her estranged daughter, suddenly enters, buying steak knives, a novelty lighter, pink mittens, beef jerky, WD-40, swim goggles, and a small wooden soldier ornament. Kimmy bags everything without scanning, later ringing up and paying for identical items herself. After Jennifer leaves, Kimmy weeps, regretting not speaking to her daughter. A tall form with an inhuman eye appears outside, frightening her.

Meanwhile, Letha kneels in the snow outside the sheriff’s office, having dropped her four daily medications. She retrieves three pills but loses a steroid tablet. Taking them requires elaborate maneuvering around her jaw brace. The Oxycodone takes effect as she fantasizes about luring South onto thin ice. Jennifer arrives on the stolen snowmobile and invites her to Terra Nova.

Lonnie, watching from his garage, plans to sue over Rexall’s earlier attack. He recalls childhood trauma from the day Melanie Hardy drowned in 1993, blaming it for his stutter. As he leans forward, his bay door shatters inward.

Jennifer and Letha speed across Indian Lake. When Jennifer loses control approaching a dock, she dives off, but Letha expertly maneuvers the snowmobile to safety. Inside Letha’s charred would-be house at Terra Nova, Jennifer tells Letha about Ginger’s Lake Witch story. Letha casts doubt on the story since Ginger’s doctors believe that Ginger resents Cinn for abandoning her during the Independence Day Massacre. Ginger may be trying to undermine Cinn with the story, especially as South’s latest massacre is beginning to center around her. Jennifer suspects Cinn may be a final girl.

Jennifer and Letha bond over slasher trivia, during which they discover that Letha now knows more about slashers than Jennifer does. Letha pressures Jennifer to embrace her old identity as the slasher expert Jade, eventually breaking through her resistance. Letha reveals that Adrienne’s first name is Linnea, after Linnea Quigley, the scream queen actress who appeared in Silent Night, Deadly Night. Jennifer confesses that her affinity for slashers helped her to deal with the fear of Tab’s abuse. Letha admits that when she rescued Jennifer from the rotting elk pile just before the Independence Day Massacre started, she found proof that her father was indeed a killer.

Dark Mill South suddenly appears in the hallway. Letha stands between him and Jennifer, holding four steak knives Freddy-style between her fingers. She throws them with expert precision, hitting South’s chest and hand. He falls but throws the knives back, embedding one in Letha’s shoulder. Letha shoves Jennifer under the sink to hide, then kicks open the back door as a diversion. South enters the kitchen, then exits through the garage instead of following Letha out the back. Jennifer escapes to the garage and sees South took hedge clippers from a pegboard, a homage to The Burning.

Galatea writes another paper for Mr. Armitage, claiming credit for the idea to use tinsel to lure Stacey Graves out at Indian Lake. She indicates that Cinn would never allow her to get into trouble, however, a character trait she inherited from her mother, Macy Todd. Galatea recounts one occasion when a high school boy approached Ginger inappropriately at a restaurant. Macy unbuttoned her blouse, lured the boy into a restroom, and emerged alone; the boy never exited before they left.

Galatea describes leaving tinsel for the Lake Witch, hoping she would wear it and shimmer in moonlight. They saw silver racing across the water, confirming she could walk on the surface. Galatea, Cinn, and Ginger made a blood oath never to reveal their secret.

Galatea recalls her experience of the Independence Day Massacre. She was fascinated by the lakeside movie screening of Jaws since she had never seen it before, despite the carnage unfolding all around them. Once the massacre had ended, Cinn found Jennifer Daniels’s horror movie videotapes, including Hell Night, in a trash bag and read descriptions from the cases to distract Galatea from her trauma. The only missing tape was A Bay of Blood, but the bloody lake itself had become that film. Galatea noticed a strand of their tinsel in Cinn’s hair and secretly removed it.

Dark Mill South recovers from the injuries sustained in his faceoff with Jennifer and Letha. He snaps apart the hedge clippers, keeping the black blade. Following the girls’ trail, he plans to skin them alive using a technique he learned watching hunters peel a deer with a truck. He saw a white spirit elk on the frozen lake earlier, taking it as an omen of success. He deduces they used a snowmobile and that one of them carries its dead owner’s key. Frustrated, he saws off a chunk of hair blocking his vision.

Letha hides in what would have been Gal Pangborne’s house to take her medication. The Oxycodone kicks in, leaving her sentimental. She records a video message for Adrienne, but stops when South materializes on the porch. Instead of cowering, Letha stands and confronts him. Her scream forces her jaw brace to crack, loosening her jaw painfully. As she is about to collapse, South suddenly pitches forward through the rotting floorboards into the basement. Jennifer stands behind him holding a blood-matted blue hammer. The house begins collapsing around them. As Letha falls, Jennifer, who now calls herself Jade again, grabs her hand and pulls her from the wreckage.

At the sheriff’s office, Banner hears Rexall causing a disturbance in holding. The phone line briefly comes back, and Banner calls the nursing home to learn about the dead high schoolers. Cinn is also reported missing from Pleasant Valley, likely drawing South away from the town. Banner finds Rexall ramming his cell wall, afraid that someone is approaching the building. It is revealed to be Hardy, who has come to warn Banner that kids are gathering on Main Street. Banner waits at the door, hoping Letha will return.

Meanwhile, Claude Armitage cross-country skis on the frozen lake wearing a mask from The Walking Dead and carrying a scythe, fantasizing about slasher sequels. His antagonistic father destroyed his horror collection years ago. He spots a light flickering in Terra Nova’s ruins.

Jade helps a wounded Letha away from the collapsing ruins. She lights a small wooden soldier with WD-40 and throws the can to create an explosion. At the Mondragon house, she discovers the snowmobile’s kill switch is missing. Unable to start it, she damages the machine with her hammer before giving up. She finds county coveralls inside and puts them on over her ski clothes, feeling armored by their resemblance to Halloween’s Michael Myers. She applies eyeliner and helps Letha onto the ice.

As darkness falls and temperatures plummet, they struggle across. Jade reflects that survival requires community, not lone heroism. South suddenly speeds past on the damaged snowmobile, having found the missing kill switch, and heads toward town. Jade realizes her hammer fell off and is frozen somewhere behind them. They encounter Armitage on skis. He removes his mask and recognizes Jade, helping carry the collapsing Letha. As they walk, he bombards Jade with slasher theories. Near the pier, they discover Lonnie’s mutilated body arranged like the opening death from It Follows. The abandoned snowmobile sits jammed under Melanie’s memorial bench. South’s large footprints lead up into Proofrock.