source
Patrick Wilson and Vera Farmiga return as paranormal investigators Ed and Lorraine Warren with one of the most sensational cases from their files. The movie starts with a fight for the soul of a young boy, David Glatzel (Julian Hilliard) being exorcised by a priest, while the Warrens and Glatzel’s family, including his sister’s boyfriend Arne Johnson (Ruairi O’Connor), look on.
The movie solely focusing on the darkest case of the Warrens' career: the real-life trial of Arne, who was found guilty of stabbing his landlord in Connecticut in 1981. Arne claims that the killing took place after he was possessed by a demon, and for the first time in U.S. history, the defendant claimed innocence due to demonic possession.
What has always made The Conjuring films stand out against the spin-offs within the universe, is the inclusion of Ed and Lorraine Warren. They are the ever-beating heart of the franchise, and it is their love that injects the series with heart and emotion. This movie puts a lot of the focus on the connection between Ed and Lorraine, and how their partnership perseveres through the darkness, no matter how obscene their investigations get. They take centre stage this time as we learn more about their relationship, including how they first met.