Major Crimes captain Park Kang-yoon (Cho Jin-woong) receives special funding to carry out his investigations and lives the life of luxury with fancy sedan, high-end condo, designer suits and accessories. A rookie named Min-jae (Choi Woo-shik) joins his unit, who happens to be very by the book. The pair becomes close as they begin investigating a new type of street drug, but Kang-yoon finds out that there is a mole within his unit, who has been compiling a case against him. As Min-jae is shown into the shady world of slush funds being used on cops, he is exposed to a secret organization within the ranks...