Overview: YEE and YUNG check the old file. They find out that the victim named MEI. She committed suicide a year ago together with her boyfriend, HON, who is a foreigner. YEE and YUNG inspect the satchel. They discover a letter which was written by MEI to FUNG (who had died 5 years ago). It depicts how they were persecuted by Butterfly. YEE and YUNG even receive a call front MEI’s spirit. She implores them to clear the case for her. They find out that both FUNG and HON did have an affair with a rich lady, TING, who has married.FUNG is the member of the Butterfly Club. He had been fallen in love with TING. FUNG had fell down from a cliff and died five years ago when he tried to catch a butterfly. HON is TING’s subordinate. CHIT is asked to investigate TING. YEE and YUNG go to MEI's school for some hints. They find out that MEI and CHIT are classmates. CHIT's plot is unveiled.