In 2008, a nine-year-old girl goes missing on a bleak council estate in the north of England. A frantic search ensues but no trace of her can be found and within a few hours the police investigation takes on the scale of a murder enquiry. Appeals by the apparently grief-stricken mother, Karen Matthews, come to nothing and yet the community, led by the indomitable Julie (played by Sheridan Smith) stand by her and make extraordinary efforts of their own to find Shannon. The case rapidly becomes one which grips the entire nation. And then, just as all hope is close to fading, she is found alive. The wild celebrations of the community are cut short when they learn that Shannon has been found with a man known to Karen Matthews. Was there a conspiracy?