Since the Beginning of Time the forces of Order and Chaos have been engaged in an eternal struggle to decide the fate of all Creation. That struggle has now come to the Mortal Realm... And neither Man, Demon, nor Angel will be left unscathed...

Diablo, Lord of Terror, and youngest of the Three Prime Evils, awoke from his long sleep beneath the dark earth. Setting in motion a grand scheme to free his exiled brothers, Mephisto and Baal, Diablo took control of the small western kingdom of Khanduras. Working from deep within the ancient catacombs beneath the town of Tristram, Diablo gripped the entire populace in a blanket of fear and paranoia.

Ultimately, as even Khanduras' good King Leoric fell under Diablo's wicked power, a lone hero arose to challenge the darkness that had engulfed the land. After plumbing the hellish depths of the labyrinth under Tristram, the nameless hero finally confronted the Lord of Terror himself. Knowing full well that Diablo's spirit could never be truly destroyed, the hero made the noblest sacrifice of all-- casting his soul and his very sanity aside, the hero took the spirit of Diablo into himself, hoping that his own strength of will could contain the demon within. The hero could never have known that his selfless act would not only ensure Diablo's victory, but would irrevocably damn his soul for all time.