Inspector Hartley Quinn, a Scotland Yard detective, relentlessly pursues the Phantom Thief Gentleman across Europe. He projects a stern, professional demeanor, intensely focused on the thief's capture.

His meticulous image is reinforced by a formal suit and glasses, reflecting his nature as a rule-bound law enforcement officer. He operates strictly by the book, adhering to established police procedures without deviation.

This pursuit brings him into conflict with the Milky Holmes detectives. He frequently clashes with their unconventional, enthusiastic, and often chaotic methods, viewing them as unprofessional hindrances to proper investigation.

His dedicated hunt for the Gentleman leads him to Japan and the Kobayashi Opera House. Here, his investigation converges with Milky Holmes as they collectively confront the Gentleman and unravel the mystery of five stolen paintings.

Throughout these events, Quinn remains unwavering in his duty and singular objective: apprehending the Gentleman. He consistently embodies traditional, protocol-driven policing, serving as a direct counterpoint to the freewheeling Milky Holmes team.