The Call Is Coming From Inside

The one rule at SaitoGemu is that phones stay off. Cooper switches his back on.

He does it to take a photograph of the test kit for Sonja, a journalist he met in a London bar. It's a small, selfish, entirely human act, and by the end of the episode it has killed him. Spoilers follow.

"Playtest" is the second episode of series three of Black Mirror, released on Netflix on 21 October 2016. It runs 57 minutes. Charlie Brooker wrote it and Dan Trachtenberg directed, and both men had worked as games journalists before they worked in screens. You can feel it in the way the episode knows exactly what a playtest is: a stranger, a non-disclosure agreement, and the polite fiction that nothing here can hurt you.

The art: a haunted house with a legal department

Cooper (Wyatt Russell) is an American travelling to avoid his mother's calls after his father's death from Alzheimer's. In London, identity theft empties his account, and the only quick money on offer is a paid test for SaitoGemu, a games company. Katie (Wunmi Mosaku) runs the session. She fits him with a "mushroom", a device implanted in his neck. First comes an augmented-reality Whac-A-Mole, which is a joke and a warm-up. Then the owner, Shou (Ken Yamamura), explains that the next game uses a neural network to tailor its scares to the player's own fears.

That is the whole machine, and it is a good one. Because the game draws on what Cooper actually dreads, the scares are specific: a spider, a figure in a painting, and a simulation of the boy who bullied him as a child. Trachtenberg shoots the sequence like a survival-horror game, with long corridors, a creaking house and the sense that the next door is the one. The spider effects came from Framestore, and the episode was nominated for a BAFTA Craft award for visual effects. The house is genuinely frightening, partly because the hardware around it stays so calm.

Russell is the reason it works. Cooper is hard to like. He ignores his mother's calls and sneaks his phone into the test. Trachtenberg has said Russell's casting made that arrogance easier to forgive, and Russell makes him boyish rather than awful, so that when the house starts taking him apart you are on his side. Hannah John-Kamen has the harder job as Sonja, who has to be believable as a person and as a hallucination, sometimes in the same scene.

The trouble is the ending. After fifty minutes of escalating dread, the episode reveals that the whole session lasted a fraction of a second. A phone call from his mother interfered with the device and killed him, and everything afterwards happened only in his head. The reveal has a cruel logic. But it also erases most of what we have watched. Critics split on it, and some called it a cheat or a dark joke. I think it works as a gag and fails as a tragedy: we are asked to grieve for a man whose suffering we have just been told was never real. That's the gap between 7 and 8.

The prophecy: the game, the implant, the call

The game that reads you. This is the part Brooker got closest to. In late September 2015, a year before the episode aired, a horror game called Nevermind went on sale on Steam. It reads the player's heart-rate variability, with a camera or a heart-rate sensor, and gets harder the more stressed you become. MIT Technology Review described it that month, and its creator, Erin Reynolds, wanted players to learn to manage anxiety rather than just enjoy it. A 2015 study of 16 players found that frightening moments show up clearly in physiological signals. The limit, as the same coverage noted, is that a pulse shows that you are stressed but not why. The version in the episode, which learns your particular dread and builds a spider out of it, is a step beyond. It is a software problem, not a hardware one, and it is the likelier route to the thing Shou describes.

The AR in everyone's pocket. In July 2016, three months before the episode, Pokémon Go launched, and Apple said it had been downloaded more than any other app in its first week. By late 2022 it had passed 600 million downloads. The Whac-A-Mole gag that opens the test would have looked like a satire of a trend and turned out to be a description of one.

The implant. Here the episode runs far ahead of the lab. The real devices read the brain far better than they write to it. A 2025 study in Cell put electrodes in the motor cortex of four people with ALS or brainstem stroke and decoded imagined sentences with accuracy of up to 74%, from a vocabulary of up to 125,000 words. The team added a password so the system would only read inner speech when its user chose to unlock it. Writing is harder. Neuralink's Blindsight, which aims to produce vision by stimulating the visual cortex, received an FDA breakthrough-device designation in September 2024 and remains experimental, with early resolution expected to be low. Nobody has shown a device that can put a convincing spider, a bully and a woman he met the night before into someone's senses at once. That's the premise of the episode, and it is a long way off.

The call. The mechanism of Cooper's death has a real cousin and a real difference. In 2021 the FDA warned that magnets in some phones and smartwatches can put certain implanted devices, such as defibrillators, into "magnet mode", and it advised keeping them six inches away. But the agency also said it believed the risk was low and knew of no adverse events. And it was the magnet, not the call. The episode's moral, that the most dangerous thing in the room was an ordinary phone, is wrong in its detail and right in its spirit.

The reading

"Playtest" is a clever, nasty piece of genre craft with a bad habit of explaining itself. As a horror episode it holds up. As a prediction it gets the culture right and the hardware wrong, which is the usual way round. What it understood best is the setup rather than the technology. A young man runs out of money, an unregulated company offers a lot of cash for a small risk, and a form says he agrees to all of it. That was the real near future in 2016, and it is not especially futuristic now.

Cooper thinks he spent a night in a haunted house. By the episode's sums, he spent less than a heartbeat. The longest night took a second, and the only thing that could stop it was his mother, who had been calling all along.