The protagonist, Chen Yuan, is a cultural relic restorer. He receives a mysterious bronze casket from an archaeological site, engraved with the words: “Neither gold nor jade, its key will reveal itself; guard the ruins, and pass the torch from generation to generation.” While restoring a damaged Warring States lacquerware piece under a particular light, he sees its patterns cast shadows on the wall that fit the designs on the bronze casket perfectly, forming the first map to a hidden realm.
