Evidence from a bloody case ten years ago resurfaces, and a silver button connects a series of murders spanning a decade. Su Wan, a sharp-eyed forensic doctor, and Chen Rui, a tenacious detective, work together and clash as they gradually close in on the truth about a chemical plant leak deliberately buried years ago. But the real culprit has used ten years of bloodshed to draw a symbol, setting a ritualistic trap with buttons... When the last button falls, can they uncover the redemption hidden behind the bloodshed?
