Paranormal investigators Ed and Lorraine Warren take on one last terrifying case involving mysterious entities they must confront.

Arthur must enlist the help of his half-brother Orm in order to protect Atlantis against Black Manta, who has unleashed a devastating weapon in his obsessive quest to avenge his father's death.

The Warrens investigate a murder that may be linked to a demonic possession.

Arthur Curry learns that he is the heir to the underwater kingdom of Atlantis, and must step forward to lead his people and to be a hero to the world.