SUM visits SZ at her memory school. SZ introduces LAI CHUN-HUNG, one of the tutors, to him. SUM and SZ have lunch together. SUM tells SZ he would not have become a cop if she had not taught him the Memory Palace memory skills when they were young. A man has jumped down from a building. SUM is astonished to learn that the man is HUNG. He concludes this is not an ordinary suicide. SZ reveals that another tutor named WILSON has once invited HUNG to join another school. She managed to persuade HUNG to stay by paying him a lot of money, but by doing so, WILSON had to pay the other school three million dollars as compensation. YIN asks SUM why he did not take WILSON back to the station. SUM says he needs to pay attention to WILSON’s microexpressions, but he fears YIN’s double charge pen spinning trick will affect him. SUM goes through the teaching VCDs of SZ’s memory school. TV host NGAI WAING-SHAN was one of HUNG’s students……