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"Chapter Four: The Sauna Test" is the fourth episode of the third season of Stranger Things and the twenty-first episode overall. It was directed by Shawn Levy and was released on July 4, 2019 along with the rest of the season.


A code red brings the gang back together to face a frighteningly familiar evil. Karen urges Nancy to keep digging, and Robin finds a useful map.



As Eleven brushes her teeth at Max Mayfield"s house, she mulls over her ominous visions of and encounters with Billy Hargrove and Heather Holloway. Max assures her that everything is alright, despite Eleven's confusion over their behavior. As Max shows her a Wonder Woman comic, a hysterical Doris Driscoll is restrained by paramedics while Nancy Wheeler and Jonathan Byers watch. She continues to insist that she "has to go back" and desperately reaches for the Brimborn Steel Works as the ambulance drives by it. Tom and Janet Holloway awaken tied up in the basement of the mill. Heather and Billy ungag them. Heather tells her father that "there's no stopping it," and Billy tells them not to move. They leave as the Mind Flayer, now in physical form, attaches tendrils to the Holloways' faces.

Jim Hopper awakens in his cabin being tended to by Joyce Byers, recuperating from the injuries inflicted upon him by the Russian. The two theorize about his origins and motive, and Joyce reveals she wrote down the man's license plate, but only half of it is accurate. Joyce mentions he was driving a motorcycle, and Hopper remembers a man in motorcycle gear emerging from Larry Kline's office. Max ignores Lucas Sinclair's frantic radio calls until Mike Wheeler calls her house phone and tells her to meet them at his place. Lucas tries to contact Dustin Henderson, who is busy staking out Lynx Transportation's covert operations. He formulates a plan with Steve Harrington and Robin Buckley to get inside their shipping room. Steve offers to fight the armed guard, but Dustin reminds him of his poor track record of losing fights. Robin gets an idea and grabs cash from the tip jar, running off.

ST3-Eleven, Will, Mike, Lucas and Max discuss

Will Byers explains the Mind Flayer's return to his friends

At The Hawkins Post, an exceptionally angry and sweaty Tom berates Nancy and Jonathan for disobeying his orders and encouraging Driscoll, who turns out to be a paranoid schizophrenic. Under threat of a lawsuit from her family, he fires them both. The kids converge and Will Byers explains his recent premonitions of the Mind Flayer's return. Eleven insists she closed the gate, but Will remembers the piece of the creature that exited him and theorizes that Eleven locked it in their world with them. He realizes it would want a new host, and the group agrees to find out who. Hopper tries to get answers out of Kline about the man who attacked him and threatens to expose his corruptions, but Kline reminds him that he knows of Hopper's previous illegal pill usage. Hopper beats Kline and threatens to cut off his finger until he explains he is working with the man, who works for the owners of Starcourt Mall. Kline raised property taxes to allow Starcourt to outcompete local businesses. Kline tells him the records of these dealings are at his mansion, but warns him the Starcourt people are extremely dangerous. Hopper drags Kline out with Joyce in tow.

Driving home, Nancy rants about the strange nature of their firing, but Jonathan insists she is convincing herself she is in the right. He berates her for devaluing the importance of his job, as she leaves in a wealthy family while he does not. She fires back that he does not understand how humiliating her job was, and they both conclude that they do not understand each other anymore. Nancy returns home in tears. Robin returns with Starcourt blueprints, which shows air ducts that lead from the ice cream parlor to the shipping room. The three are initially excited, but realize none of them can fit in the vents. Erica Sinclair arrives demanding more free samples, and Robin looks at her and gets an idea. The kids observe Billy at the pool, who has covered the unshaded parts of his body. Mike remembers the Mind Flayer's avoidance of heat, and Will explains that the Mind Flayer is keeping Billy dormant until it needs him. Deciding they cannot risk him activating and attacking more people, the boys head into the locker room and formulate a plan to trap Billy in the pool's sauna after hours.

Erica checks the vents, confirming she is able to fit but demanding compensation. The group bribes her with "free ice cream for life" at her request, and she agrees to cooperate. Kline shows Joyce and Hopper the financial records and again warns them that the Starcourt men are dangerous. Joyce notices a correlation with the bought properties: they are all close to the power plant. Hopper finds Kline trying to escape through his window and handcuffs him to his bed. When his wife later comes home, he shouts at her to bring him a phone. Karen Wheeler listens to Nancy explain what happened, and tells Nancy she understands why she did not want to be wrong: because then she will be perceived as what most people already see her as. Nancy insists she gets her determination from her mother, and Karen tells her she is proud of her and that she should finish the story.

S03E04 - Erica moving through Starcourt Mall air ducts

Erica Sinclair crawling through the Starcourt Mall ventilation system

The kids prepare to trap Billy. Lucas tries to talk to Will about the previous day, but Will brushes him off, while Mike explains Hopper's interference in their relationship to Eleven in hopes of making up with her. Eleven muses that Hopper may be right that they are spending too much time together and quotes something Mike said while she spied on him in the void, shocking him.


Max keeps watch over Billy, hoping he is not the host. Erica crawls through the vents of Starcourt and opens the Lynx Transportation door, and her group comes down from the roof to join her.

S03-Will, Mike, Eleven, Max and Lucas

The kids trap Billy Hargrove in the sauna

Mike lures Billy to the sauna using his voice and a CPR dummy and Eleven stuns him by throwing him against the wall. The kids lock the door with a pipe and chain. Billy and Max lock eyes for a moment and he silently pleads with her, and Max orders the group to turn the sauna on, which they do. Nancy sneaks into Driscoll's hospital room and looks at her medical chart, finding something that catches her attention. Driscoll's heart rate suddenly spikes and she begins breathing heavily, implied to be a result of Billy's predicament. The Starcourt group extracts a green liquid in a canister from the marked boxes. Before they can examine it, the room shudders and when they attempt to operate the control panel to open the door, it plunges downwards, revealing it to be an elevator.

Chapter Four - The Sauna Test

Billy aggressively demands to be let out as the sauna reaches maximum temperature. He begins to weep, apologizing to Max for the things he has done and insisting that the "giant shadow" made him do them. As Max tries to comfort Billy through the door, he subtly grabs a piece of broken tile and the skin on the back of Will's neck flares up. Mike screams for her to get away from the door just as Billy shatters the glass on it, trying to stab her. He removes the pipe blocking the door and Lucas shoots him in the head with his Wrist Rocket. The lights start to flicker and Billy's veins blacken, and the lights in the hospital and Driscoll do the same. Billy breaks open the door and Eleven pins him to the wall with a barbell. He overpowers her and begins to strangle her until Mike attacks him with the pipe, breaking his concentration long enough for Eleven to throw him through the wall. Mike briefly holds her, and the kids watch in astonishment as Billy runs away.

In the basement of the mill, Billy confirms to Heather that "the girl" was the one who attacked and nearly killed him, and his identity as the Mind Flayer's host is now compromised. Heather calmly tells him that Eleven cannot kill all of them, revealing a dozen people standing before the Mind Flayer.


The official teleplay for "The Sauna Test"



Also Starring




  • "We'll Meet Again" by Vera Lynn - El, Mike, Lucas, Will and Max watch Billy run away after the Sauna Test.

Original score

  • "Happy Screams" - Eleven shares her continued worries about the state of Billy and Heather with Max.
  • "Lights Out" - The monster approaches Heather’s parents.
  • "Tendril" - Heather’s parents become flayed.
  • "The Ceiling is Beautiful" - Hopper wakes up in the cabin.
  • "Code Red" - Mike, Lucas and Will attempt to gather the other members of the party to them.
  • "Looking for a Way Out" - Robin takes money from the tip jar and leaves to find a way into the loading room.
  • "Six Facts" - Tom yells at Nancy and Jonathan before firing them.
  • "We Don't Understand Each Other" - Nancy and Jonathan argue in the car.
  • "Blueprints" - Robin, Dustin, and Steve form a plan using the blueprints Robin had acquired.
  • "Leap of Faith" - Mike forms a plan to lure Billy into the sauna.
  • "Land Deeds" - Mayor Kline retrieves the land deeds from his safe in his mansion.
  • "Theoretically" - Joyce explains to Hopper the machine responsible for disturbing the electromagnetic field must be located at one of the properties Mayor Kline has deeds to.
  • "You're a Fighter" - Karen consoles Nancy.
  • "A Familiar Shape" - The kids taunt Billy in order to lure him to the sauna.
  • "Turn On The Lights" - Billy finds who he thinks is taunting him.
  • "Making Contact" - Billy enters the sauna.
  • "They Found Us" - The kids lock Billy in the sauna.
  • "Possessed" - Nancy sneaks in to Doris Driscoll’s hospital room.
  • "Not Chinese Food" - Steve opens a box and finds a mysterious green tube before the room/elevator they’re in rapidly descends.
  • "Mirkwood" - The Mind Flayer activates Billy, which leads to him breaking out of the sauna. Doris Driscoll begins to scream. Eleven tries to fight Billy off.
  • "Sauna Test" - Eleven sums up the little strength she has left by throwing Billy through a brick wall, saving Mike’s life in the process.
  • "I Can Save Them" - Eleven collapses in Mike’s arms as Billy makes a run for it.

Behind the scenes

The Sauna Sequence

Director of the episode, Shawn Levy revealed that the sauna sequence between Billy (Dacre Montgomery) and the kids required at least three months of story-boarding and stunt choreography before the team started shooting it. He explained that they spent entirely four days, 10-12 hrs everyday, in the set working out the scenes. He also had to film the entire sequence with Millie, Dacre, Finn, Noah, Caleb and Sadie using only two handheld cameras for maximum intensity. While commending Millie Bobby Brown and Dacre Montgomery for their sublime performances, Levy also revealed that when Eleven (Millie Bobby Brown) collapsed into Mike's (Finn Wolfhard) arms at the end of the sequence, it was due to real exhaustion of the actress.[1]


Shawn Levy and Dacre Montgomery, during a read-up of the sequence.

The only scene where a stunt double was required was when Billy was pinned to the wall with a barbell to get a wider view. Excluding the scene, the whole fight sequence was filmed with Millie and Dacre. Levy also mentioned that the moment when Billy was getting possessed by the Mind Flayer, it was Dacre Montgomery’s idea to have Billy’s feet dragging on the floor, which he shot a full on close-up.[1]

Since the sequence had no dialogue, Levy played out some original scores from the first and second seasons of Stranger Things, so that the actors could get in the mood of the horrific sequence.[1]


View Gallery For this subject's gallery, see The Sauna Test/Gallery.


  • On December 9, 2018, a teaser trailer for the third season was published across social media, listing the titles of the eight episodes, the fourth of which was "The Sauna Test".
  • This is the only episode in the season where Grigori does not appear.
  • Max owns various issues of DC Comics: Wonder Woman #324, #325, and #326, as well as Green Lantern #184, #185, and #188.