Summary
Highlights
Barb, an old woman, drives in snowy weather with a picture of a young couple, heading to Lake Hilda. She gets lost and finds an isolated house where she encounters an old man and a bloodstain. After he gives her directions, she arrives at the frozen Lake Hilda, a place of sentimental value. While drilling a hole on the ice, she hears gunshots and witnesses the old man shoot and drag a young girl into his house. Barb's car gets stuck in the snow, forcing her to return to the house where she finds the girl chained in the basement, and another woman, the 'Purple Lady,' joining the old man.
Barb writes a message of reassurance on the basement window for the kidnapped girl. The Purple Lady discovers Barb's mitten and a message on the window, realizing their secret is compromised. Barb sets a trap for the old man at the lake, then attempts to rescue the girl. She soaks the house to create a diversion. However, the Purple Lady shoots Barb in the shoulder outside the house. Upon their return, the couple finds their house soaked, infuriating them further. Barb realizes her wedding ring is missing somewhere in the house, a ring given to her by her deceased husband, Karl. She finds a handgun left by the old man and prepares for confrontation.
The kidnappers, a terminally ill Purple Lady and her hypothermic husband, plan to harvest the girl's organs at the lake. Barb communicates with emergency services from a car radio. The old man, confronted by Barb, reveals he was coerced by his wife into the kidnapping, and is hypothermic. He returns Barb's missing ring. Barb, touched by his story, sends him to Wannaska to report everything to the police and seek medical help. His wife, enraged by his defiance, finds him and murders him when he refuses to continue with her plan. Barb sets her car on fire to draw in authorities.
Two rangers arrive, but do not heed Barb's warnings about the Purple Lady, who ambushes and kills them both. Barb manages to retrieve her gun, wounding the Purple Lady, but runs out of bullets. As she reloads, she discovers the old man's body, murdered by his wife. Barb is knocked unconscious by a falling beam. She a flashback of her husband's death and awakens in the basement with the kidnapped girl, Leah. Barb, identifying with Leah's name due to a past dream of naming her daughter Leah, uses a handle from her box to free herself and Leah from their chains. They try to escape, but the Purple Lady traps them again.
Barb has another flashback, remembering her husband's wish to have his ashes scattered in Lake Hilda. The Purple Lady brings Barb and Leah to a tent on the lake, revealing a cooler for organ transport. She intends to extract Leah's liver. Barb offers herself in Leah's place, but is refused. As Barb is forced to tie Leah, she intentionally leaves the bonds loose. While the Purple Lady prepares for the surgery, Barb attacks her. During the struggle, a lantern tips over, igniting the tent. Barb overpowers the Purple Lady and throws her out. Leah, using the screw Barb gave her, escapes the burning tent. Barb pulls the Purple Lady into a hole in the ice, sacrificing herself and scattering Karl's ashes, while Leah walks away in shock.