The game begins with an amnesiac Edward Carnby, a paranormal investigator recovering from an exorcism performed on him by a group of occultists led by Crowley. A guard is instructed to take him to the roof for execution, only to be dragged away and slaughtered by an unseen force. He wanders the collapsing building in search of an exit; witnessing several people being killed in a similar fashion as the guard, as well as a young woman becoming possessed by a demon which claims to know of his past. After battling the entity, he meets art dealer Sarah Flores. They make their way to the basement parking garage where they meet Theophile Paddington, the occultist who performed Edward's exorcism and an old apprentice and friend of Carnby's. Theo explains the nature of the Philosopher's Stone and Crowley's desire to unleash its evil power.