Snow falls in the Forbidden City, and young painter Rong Qing is ordered to paint a portrait of the deposed prince Yinreng. Using his pen as a blade, he hid a secret message to reverse the case deep in the prince's pupils, but accidentally triggered the "twin mirror" that spans time and space. In the mirror, the souls of the young man and the middle-aged prince are intertwined; outside the mirror, a secret sealed by cinnabar slowly emerges. When the arrow of history shoots towards the future, the only person who can catch it is a painting viewer three hundred years from now.
