Several centuries in the future, a meteor collision with Earth throws up clouds of dust that block out the sun. The remaining survivors seek refuge beneath small openings in the clouds, where light can still be found. Those who remain in the dark earth are hunted by strange creatures infected with the darkness.

To protect themselves, people build cities beneath the light called stallites. By the time of the game, most citizens have forgotten their history and worship the light as a god. The stallites are run by Sun Priests, who maintain order and keep the creatures of darkness from harming the city.

The story follows Arkhan, a guardian of fire and protector of the stallite Sparta and the Sun Priests. After an attack on the Sun Priests, he is poisoned and begins to mutate into a creature of the dark. He must find a cure before the transformation is complete while uncovering the conspiracy behind the attack.