After William Garrin, a mercenary, is held captive in prison, he figures a way to defeat the monsters that attack the Great Wall

During the reign of Renzong Emperor a group of European mercenaries travels to China searching for the secret to gunpowder. A few miles north of the Great Wall they are attacked by a monster. Only Irishman William Garin and Spaniard Pedro Tovar survive. They sever the monster's arm and bring it with them. Upon reaching the Wall they are taken prisoner by the Nameless Order. Led by General Shao and Strategist Wang the Nameless Order exists to combat Tao Tie, alien monsters that arrived from a meteorite and attack once every sixty years.