Jenna, played by Scout Taylor-Compton, finds herself deeply overwhelmed by her past after a tragic car accident that resulted in the death of her boyfriend, Jamie. The incident leaves her struggling with grief and emotional scars, which she tries to cope with as best as she can. Three years after the tragedy, Jenna’s close friend Renee, portrayed by Christina Ulloa, invites her to spend a weekend at a serene lakeside cabin. The invitation is meant to offer Jenna a chance to relax and escape her pain, and she agrees, hoping to find some peace away from her memories.
Once at the cabin, they are joined by Renee’s boyfriend Michael, played by Michael Copon, who is known for his carefree but reckless personality, and his friend Ian, played by Travis Van Winkle, who is more cautious. The group is warmly welcomed by Wade, played by Tyler Mane, who owns the cabin, along with his friendly dog, Beau. Wade introduces himself as someone who often spends his weekends at the lakeside, and he seems like a helpful, approachable host. The group quickly settles into their surroundings, excited about the upcoming town festival and the celebration planned for the night.
During their stay, Wade mentions that his work might keep him away during the evening, hinting at his busy schedule, but the group is more interested in enjoying themselves. Later, they discover a sauna Wade built himself, which becomes a focal point of their evening. They are intrigued and decide to use it, which leads to an amusing yet tense experience. Outside, they enjoy the cool lake water after enduring the sauna’s heat, but the temperatures inside the sauna begin to skyrocket, creating an increasingly dangerous situation.
As the heat intensifies, Michael, who had earlier been affected by marijuana Wade supplied, becomes more agitated and refuses to leave the sauna. Renee, at first, tries to leave but finds the door blocked from the outside, making her panic. Initially, the group dismisses her fears, thinking Michael is playing a prank, but it quickly becomes evident that they are trapped inside. They attempt to break the small window in the door, but Ian injures his hand in the process. The rising temperatures make it harder to breathe as everyone struggles for air, and their desperation grows.
Meanwhile, Wade is shown managing fireworks for the festival, unaware of his friends' peril. His dog, Beau, tracks the faint screams for help from the sauna, but Wade dismisses it, thinking the others are at the party or joking around. Michael, meanwhile, returns to Wade’s cabin, noticeably intoxicated and detached, revealing that he believes the group went to the festival, not realizing the danger they are facing. He discusses his night and admits that he didn’t have a ticket to the party, indicating his disconnection from what’s happening with his friends.
Back at the cabin, the tense situation inside the sauna escalates as the temperature continues to rise. Renee, feeling weak and sick, decides to break the controller, hoping it will lower the heat, but Jenna intervenes to prevent her, leading to a heated argument. During the argument, Jenna accidentally hits her head on a hot rock, rendering her unconscious. Panicking, Jenna then attempts to destroy the controller herself, causing the sauna’s interior to heat up dangerously. Ian, in an effort to stop the rising temperatures, burns his own body, which results in an explosion that kills him but provides a brief moment of relief.
Despite everything, Jenna manages to escape the sauna, but she is severely wounded and disoriented, experiencing hallucinations of her friends suffering and dying. With Renee’s help, she is positioned near the broken window to breathe. The event reveals the true horror of their situation and Jenna’s fragile state of mind.
Meanwhile, Michael, unaware of his friends’ plight, returns to Wade’s cabin. Flashbacks and scenes show how he was so intoxicated earlier that he unintentionally knocked over equipment near the sauna door, which ultimately trapped his friends inside. Wade later finds Jenna and Renee alive and injured outside the sauna, and emergency services are called. Paramedics arrive promptly, and Jenna and Renee are loaded onto stretchers, holding hands in silent support, as they are taken away for treatment.
This harrowing experience in the sauna becomes a story of survival, guilt, and the terrifying consequences of recklessness, leaving viewers with a stark reminder of how quickly a situation can turn deadly when control and safety are compromised.
