Yun Xiu, a lantern maker, creates the Heart-Reflecting Lamp, a magical lantern capable of revealing people's innermost thoughts. However, she soon discovers that it recklessly pries into other people's private thoughts, causing all sorts of complications. Together with her apprentice, Qiao Kui, she repeatedly tests and modifies the lamp, establishing boundaries and rules along the way. They come to understand that the lamp should only reflect one's own heart and must never make decisions on anyone's behalf. In the end, the extraordinary lamp learns restraint and returns to being an ordinary source of light, once again becoming part of everyday life. Everyone has their own private world within their heart; there is no need to use lamplight to pry into it. Keeping true to one's own heart is what truly brings peace to the world.