A family living in a north London council house during the late 1970s begins experiencing disturbing and increasingly violent supernatural phenomena, centring on one of the young daughters who appears to be possessed by a malevolent spirit. Paranormal investigators arrive to document the case, which draws widespread media attention and divides opinion between those who believe the haunting is genuine and those who suspect the children of trickery. The drama is based on the real-life Enfield poltergeist case, one of the most well-documented and controversial alleged hauntings in British history.