In 1981, only a few years after Michael Taylor's particularly violent Ossett Murder case that shocked the United Kingdom, and Janet Hodgson's blood-curdling Enfield Haunting case in The Conjuring 2 (2016), the experienced investigators of the unexplained, Ed Warren and Lorraine Warren, found themselves in Brookfield, Connecticut. There, Ed and Lorraine encountered something they'd never seen before: after the challenging exorcism of eight-year-old David Glatzel, Arne Johnson, a young friend of the Glatzels, began exhibiting increasingly strange behaviour. Then, more and more, the suffocating stranglehold of evil tightened around everyone involved, leading to murder and Johnson's incarceration. But, according to Arne, evil forces were at work. Did the devil, indeed, made him do it?