When the present you meets the past, what kind of mystery will the future bring? When she was a student, Yun Xiao Xi was framed for plagiarism and had to experience her mother's death on the same day. Having never recovered, she now lives a downtrodden and lonely life as an outcast, despised by her boss and colleagues. One day she receives a "pill of regret" from a mysterious person. It allows her to travel into the past to correct her past cowardice and completely change her life.