We all know a Cooper (Wyatt Russell): He's the friendliest guy in the hostel. He's got scars from running with the bulls in Pamplona. He can't be bothered to take his grieving mother's phone calls, but he's got the time to pick up a girl on a dating app while traveling in London, the last leg of a trip around the world. The date with Sonja (Hannah John-Kamen) leads to the bedroom. The next morning, he tells the British tech journalist that his father has recently died from Alzheimer's. He has a strained relationship with his mother, hence his inability to pick up the damn phone. This is a guy who probably sits in the front of a taxi so he can talk to the driver — and he can't tell the woman who birthed him hello? Red flag, Sonja. Red flag. In the meantime, Cooper's got bigger problems to deal with. He's ready to fly back home, but his bank account seems to have been cleaned out in an identity theft situation. Rather than call his mom like a smart boy, he heads back to Sonja's flat and ponders how he'll raise some money. She conveniently spies a classified ad for a "thrill-seeker" opportunity at Shou Saito's gaming company. Saito, she shares, is a huge gaming genius who has been highly secretive about his latest project. If Cooper could sneak a photo of the game, he'd be able to sell it for big bucks. What could possibly go wrong? A lot, apparently. Cooper manages to snap a quick pic of the gaming device and send it to Sonja while the no-nonsense assistant, Katie (Wunmi Mosaku), fetches his NDA. In addition to agreeing to having a medical procedure as part of the testing ("It's no more invasive than having your ears pierced," Katie assures him.), he must hand over his phone. Katie assumes she's switched it off, but thanks to Cooper's sneaky snapping while she was out of the room, it's still on. His mom calls just as Katie's implanted a "mushroom" into the back of his neck.
The mushroom allows gamers to experience an interactive augmented reality that Katie likens to "layers on top of reality." First up is a whack-a-mole game in which discs transform into an animated 3-D gopher that only Cooper than see. He's into it and doesn't balk when Katie suggests he could make more money by testing out a full game rather than a demo. Cooper then meets Saito himself (Ken Yamamura), who expresses an interest in how and why gamers get a rush. Gamers feel safe despite the thrill of their participation, which is why he's working on what he dubs "the most personal survival horror game in history." Software is uploaded to the mushroom, at which point the user is scared by the thoughts in his or her own head. To make it even spookier, Katie drives Cooper out to an old gamekeeper's lodge. She gives him an earpiece, explaining that she'll be listening from the control room. All he has to do is stay in the house for as long as possible. Everything freaking him out is merely audiovisual and can't actually hurt him, she claims. They choose a safe word and she leaves him to enjoy his non-alcoholic red wine in peace. It turns out that Cooper's big fear is a spider. He sees one and panics, but it's just his mind playing tricks on him. Then, he hears footsteps and is confronted by a creepy guy he identifies as Josh Peters, a bully from high school. Eventually, he runs into a giant spider with Josh's face. It's terrifying — and a bad time for Katie's connection to cut out. Suddenly, there's a loud banging at the door and Sonja appears. Unlike Josh, Cooper can feel her body. She warns him that he's in danger and that Saito is working on a computer-brain interface that has been linked to the disappearance of five "thrill-seekers." He grows suspicious when she says she tracked him down using his phone, given that it's turned off and not in the house. In response, she grabs a butcher knife and admits to cloning his bank card and luring him to the job ad. Another virtual spider appears as Sonja drives the knife into Cooper's chest. He reacts by ripping her face off and stabbing her with the knife that's still in his body. Ouch. But, hey! It was just a dream. Katie is back. She insists that Cooper is the one who wasn't responding. He wants out, so she directs him to the access point upstairs. Once he makes it there, though, Katie informs him that there is no access point. She taunts him about his father's illness. He can't remember, though, as the software is overriding his memories. Forget spiders and bullies — getting Alzheimer's like his father is Cooper's real worst fear. Katie and Saito burst in just as he's about to cut out the mushroom with a shard of broken glass. He's told that the program has taken root in his brain and can't be removed, leaving him without a memory. Saito apologises and tells security to put him with "the others." But, hey! That, too, was just a dream. Cooper hasn't even made it to the lodge. He's still in Saito's office, screaming his head off. According to Katie, he's only had the software on for one second. The mushroom is removed and he goes home to find his mother weeping and calling out for him. But maybe that, too, was just a dream. There's another flash and it's 5:38 p.m., right when the mushroom was first implanted. The test begins as Cooper's phone rings, his mother calling. The interference from the phone, which Katie was sure she's turned off, caused his brain to stroke out. After .04 seconds, Cooper has died. The lodge, the spiders, Josh — none of it happened. The lesson here, kids? Call your mother.