Li Mo, the administrator of the Municipal Archives, works every day to sort out the local chronicles and dust after the founding of the People's Republic of China. Until he found a 1958 "Yuejin Commune Hydrological Observation Record" among a batch of "worthless materials" waiting to be destroyed. The record is not ink, but some kind of metal powder that changes color when exposed to light. On the last page, an incomprehensible geometric figure was drawn, with a line of small words next to it: "They are watching us from the back of the moon." That night, silvery, flowing topological structures began to appear in front of Li Mo's eyes, and regular pulse signals from deep space could be heard in his ears. He discovered that he could "understand" the codes of non-terrestrial civilizations, and could "sense" metal creations buried underground in cities that did not belong to this era. The deputy director of the archives, an old man who always smiled, began to "drop in" by his office every day, using his too clear eyes to look at the silver powder on his fingers that could not be washed away.
