Warning: this review contains spoilers In June 2016, reports began to come out of the University of Oregon that computer scientists had created a device to visualise human thoughts. It measured small changes in blood flow in an area of the brain that processes visual cues and another involved in the formation of memories. With it, scientists were able to create images of faces that had been looked at by the test subjects, with interesting, if variable, results. Black Mirror: Crocodile (Netflix) takes the basic idea of that device – something that would once have been considered pure science fiction – and runs with it. It's set in Scandinavia. An investigator, Smriti (Kiran Sonia Sawar), arrives in a small town to test the veracity of an insurance claim by a classical musician who has suffered loss of earnings after being struck by a van on the eve of a major tour. She uses a device to picture the memories of the musician as he recalls them, as well as those of eyewitnesses. But Smriti’s search for witnesses gradually brings her into the orbit of Andrea Riseborough’s Mia, a successful architect with a dark secret in her past. One night, driving back after a rave, she and a boyfriend had struck and killed a cyclist on an empty stretch of mountainous road. He had talked her into dumping the body in a fjord to avoid prosecution. She has lived with the guilt and shame ever since. But when he turns up in her hotel room, saying that he had decided to write to the wife of his victim in response to a treatment programme, Mia’s survival instinct takes over. The fight or flight reflex, located in the oldest part of the human mind – the reptile brain – sees a way to stop him from telling anyone… anything. Then that pesky insurance investigator knocks on her door, the device is prepared, and out pop those bad, bad memories. There is nothing else to be done, but bump her off as well. A still from 'Crocodile' It's a pretty hoary old plot: the killer who kills again to protect herself. But writer Charlie Brooker goes out of his way to suggest that murder is not part of Mia’s personality, but there in all of us, a long way down, in the most ancient part of us. She was an unwilling participant in the original cover-up, with everything to lose from the truth being revealed, a brilliant career, reputation, financial success, and a happy home life with a loving husband and son. The compass of her life points away from violence, not towards. Riseborough is brilliant at each of the component elements that make up this story – at her most chilling when Mia is standing over Smriti with a log weapon, reasoning tormentedly that there is no alternative but to kill her. The story is told with a relish for the enveloping darkness, the murders becoming successively more troubling, and in the case of Smriti’s partner, who is hammered to death in the bath, more graphic. The sombre mountain backdrop suggests an epoch long before human time. Black Mirror: every episode ranked and rated The memory tool itself is reminiscent of the Voight-Kampff machine from Blade Runner, used to test for replicants, and the sequences with it are a fascinating example of how science-fiction does not need vast budgets to play with interesting ideas. Ultimately, it's all a little too predictable, the intersection of technology with flawed humanity bringing about an expected response. Though there's a lot to enjoy, this is definitely one of Black Mirror’s lesser episodes. read more Disclaimer: Chances are that this post was requested by an advertiser.