Ed and Lorraine Warren, the famous ghost hunters, are helping perform an exorcism on a young boy.
In order to save the child, a teenage family friend pleads with the evil spirit to enter him and leave the young boy alone. Soon, strange things start happening to the teen and he kills a friend, while in a trance. Now, standing trial for murder, the Warrens try to clear his name, by reason of demon possession. Can they gather the necessary evidence to prove him innocent?