Unable to Let Go

A woman is murdered in the street. Before she dies, she writes down three characters: "Chen Xuelin." It seems as if the killer is right in front of them, but the police discover that the message the victim left behind appears to point to a university professor who died many years ago.

Their investigation reveals that Chen Xuelin was a respected man in life. For reasons unknown, he was murdered by one of his own students. As the investigation deepens, police captain Li Zhong realizes that her death was not a noble act meant to clear the victim's name. It was meant to expose the crimes he committed, because she could never let them go.