Arthur McLennan is an inspector with the Shanghai International Police. Although he can be lenient toward petty thieves—especially if it allows him to recruit them as informants—he is one of the few police officers in the city who can be considered honest. However, this integrity, along with the horrors he has witnessed and experienced, have taken a heavy toll on his mental state; indeed, McLennan is disillusioned and has depressive tendencies, which lead him to drink heavily.
Promoted to inspector at age 20 in 1918, he is the youngest ever appointed in the city. His experience gives him an incredible analytical mind, which he uses wisely to track down murderers and human traffickers.