The Great Wall tells the story of William (Matt Damon), a mercenary who finds himself in 15th-century China. While on a mission to retrieve a valuable treasure, William stumbles upon a group of soldiers building the Great Wall of China. He soon discovers that the wall is being constructed to protect the country from a horde of monstrous creatures known as the Mota. These creatures are hell-bent on destroying China and are relentless in their pursuit.