林保怡
Bowie Lam portrays Linus Yiu Hok-sum (姚學琛), the unit's Senior Inspector. He studied microexpressions and applied psychology at an unspecified university in the United States for half a year before returning to Hong Kong as West Kowloon Police Department's new CID senior inspector. His addition to the unit sparks mixed reactions from the team members, especially Chow Fun, who disapproves his methods of investigation, slamming them as ridiculous methods. Hok-sum, however, does not seem to mind Chow Fun's obvious lack of respect and continues to peacefully and productively work with the unit members. He quickly befriends Ma-dam, who later becomes his love interest.