In the distant past, a group of European mercenaries are in the Far East in search of the mythical black powder that turns "air into fire", it the source of their future wealth in bringing it back to Europe. They are attacked by an unknown creature, with William, one of the mercenaries, able to kill the creature. Two of the mercenaries, William and Tovar, are captured by the local army, called the Nameless Order, who house them within the confines of the Great Wall.
