Kevin and his wife Suzie have been separated for two months, and in a bid to repair their relationship they plan a romantic weekend away. To Suzie's dismay, she learns he is taking her to her father's lake house in the town of Wapanoga, a place she has avoided for over twenty years because of traumatic memories that linger in the place. Unbeknownst to her, Kevin has enlisted his friend Ernie to stage a home invasion so that Kevin can step in and appear heroic, hoping this staged rescue will rekindle their connection and win her back.
Kevin's plan begins to fray when Suzie insists on going out for a drink instead of staying at the house, and he cannot reach Ernie due to the area's poor phone reception. At a local bar, Suzie reconnects with her former best friend Heather, now the town's police chief, while Kevin realizes Ernie is also in the bar and confronts him about hiding in the background. Suzie confides in Heather that she is unhappy and senses that something is wrong with her, though she cannot name what it is. Heather later drives Suzie home, while Kevin returns separately, still absorbed in reviewing the script for the staged invasion. Distracted, Kevin crashes his car and is delayed in getting back.
Meanwhile, the unsuspecting Suzie is attacked by Ernie in the house, and she kills him in self-defense. On his return, Kevin hides Ernie's belongings to conceal his involvement, a detail Heather later zeroes in on. As Kevin is seen with Ernie, Heather grows more suspicious of him. Suzie's former fiancé, Stu, arrives to act as her defense attorney, which unsettles Kevin, who suspects Stu may still harbor feelings for Suzie.
Later, Heather overhears an elderly couple recounting an incident involving Suzie during her teenage years. She confronts her father, the town's former police chief, who reveals that Suzie killed Gregory Doyle—a violent bully who tormented her and Heather—in self-defense at the lake house. He suggests that Suzie provoked Gregory into attacking her and smiled in the aftermath. Following the incident, Suzie was sent away to the city. Heather's father also admits that Suzie frequently wrote letters to Heather afterward, but he destroyed them.
Ernie's car is discovered, revealing his identity, and his brothers Victor and Oscar arrive to identify the body and learn that Ernie was seen with Kevin. As Kevin and Suzie prepare to leave Wapanoga, Stu discovers Ernie's hidden belongings, confirming Kevin's involvement. Distraught by Kevin's deception, Suzie leaves with Stu, but the pair are abducted by Victor and Oscar, who mistakenly believe Stu is Kevin. They take Suzie and Stu onto a boat and try to force Suzie to confess to intentionally murdering Ernie. Stu lunges at Oscar, causing Oscar's gun to discharge accidentally and kill Stu. Suzie jumps from the boat and returns to the lake house, while Kevin calls Heather and confesses his involvement, prompting her to head to the house.
Back at the house, Suzie passionately kisses Kevin and admits that she deliberately killed Gregory. She explains that therapy afterward conditioned her to see herself as a victim, but defeating Gregory made her feel alive—an emotion she had been missing until the staged invasion and the looming threat of Victor and Oscar. Heather arrives and holds Victor at gunpoint, but Oscar fatally impales her with an axe while Suzie fails to warn her. Suzie then kills Victor and Oscar. As Heather dies, Suzie tearfully admits that she never stopped thinking about Heather and was hurt that Heather never replied to her letters or thanked her for killing Gregory.
When the police arrive, they are told that Heather died heroically after killing Victor and Oscar, the masterminds behind the home invasion. Suzie tells Kevin that she is fortunate to have him because he accepts her true nature. As the couple drives away from Wapanoga, they clasp hands and smile.
