A mysterious plague has swept the land of Parthoris, taking the sanity of those it does not kill. Corvus, the protagonist of the first game, is forced to flee his hometown of Silverspring after the infected attack him, but not before he is infected himself. The effects of the disease are held at bay in Corvus’ case because he holds one of the Tomes of Power, but he still must find a cure before he succumbs.
His search leads him to an ancient Seraph named Morcalavin. Morcalavin is trying to reach immortality using the seven Tomes of Power, but he uses a false tome, as Corvus has one of them. This has caused Morcalavin to go insane and create the plague. During a battle between Corvus and Morcalavin, Corvus switches the false tome for his real one, curing Morcalavin’s insanity and ending the plague.