The fourth episode of Stranger Things 3, titled “The Sauna Test”, brings the kids face-to-face with a terrifying truth. The group confirms their worst fears about Billy Hargrove and the return of the Mind Flayer in one of the season’s most intense sequences. Meanwhile, other Hawkins residents uncover dangerous secrets lurking beneath the town.
Story Recap
The episode opens with Eleven struggling with the memory of her recent encounters with Billy and Heather. While Max tries to reassure her that everything is fine, Eleven remains convinced something is very wrong. At the same time, Nancy and Jonathan watch as Mrs. Driscoll is taken to a hospital, screaming about having to “go back.” Meanwhile, Heather’s parents are held captive at the steel mill, where the Mind Flayer attacks them with its tendrils.
After being beaten by a Russian agent, Hopper wakes up at his cabin with Joyce tending to his wounds. They realize the attacker was the same man Hopper saw leaving Mayor Kline’s office. Hopper confronts the mayor, who reveals the man works for the owners of Starcourt Mall. The mall owners have been buying up property around Hawkins, and Joyce suspects one of these locations houses the machine causing the town’s power problems.
Mike calls the group together for a “Code Red” meeting. Will Byers explains that the part of the Mind Flayer that was inside him never returned to the Upside Down. He believes the creature is now looking for a new host. The kids spy on Billy at the community pool and notice he is covering his body to avoid the heat. Remembering the Mind Flayer’s weakness, they devise a plan to trap Billy in the pool’s sauna after hours.
Dustin, Steve, and Robin continue their investigation into the Russian operations at the mall. With help from Erica Sinclair, who crawls through the air ducts, they break into a secret storage room. Inside, they find canisters of a mysterious green liquid. Before they can escape, the room turns out to be an elevator that plunges deep underground.
Nancy and Jonathan are fired from the Hawkins Post by Tom, Heather’s father, who appears different and hostile. Jonathan blames Nancy for getting them fired, leading to a heated argument. Nancy finds support from her mother, Karen, who encourages her to keep fighting for the truth. Nancy then visits Mrs. Driscoll in the hospital, where the elderly woman begins having a violent reaction at the same time Billy is tested.
The Sauna Test
The kids put their plan into action as the pool closes. Using a CPR dummy and Eleven’s powers, they lure Billy into the sauna and lock him inside with a pipe and chain. They turn the heat up high, hoping to force the creature to reveal itself.
At first, Billy reacts with anger, demanding to be let out. As the temperature rises, he breaks down emotionally. He cries and apologizes to Max, saying a “giant shadow” made him do terrible things. For a moment, it seems the real Billy is breaking through.
The situation turns dangerous when Will feels the Mind Flayer activate. Black veins spread across Billy’s body, and he smashes through the sauna door with supernatural strength. He attacks the kids, focusing on Eleven. He overpowers her and begins choking her until Mike hits him with the pipe. Eleven uses her powers to throw Billy through a brick wall, and he escapes into the night.
Episode Impact
The sauna test confirmed the group’s worst fears: Billy is possessed by the Mind Flayer and has become extremely dangerous. Director Shawn Levy revealed that the sauna sequence required months of storyboarding and stunt choreography. The scene was filmed over four days using handheld cameras to maximize intensity.
Dacre Montgomery’s performance as Billy received high praise. He showed a wide range of emotions, from vulnerability to pure terror, giving depth to a character who was previously mostly a villain.
The episode ends with Billy returning to the steel mill, where Heather tells him Eleven cannot kill “us.” The camera reveals dozens of possessed Hawkins citizens standing with the Mind Flayer, showing the creature has built an entire army.
The fourth episode shifts the season into high gear, raising the stakes for everyone in Hawkins. The kids now know the Mind Flayer is back and more powerful than ever. The adults are closer to uncovering the Russian conspiracy operating beneath the mall.
