Detective Ma Seok-do and his team are promoted to Metropolitan Investigation Unit where they investigate the death of a woman named Go Sun-hee and learn from the autopsy report that Sun-hee had been taking a drug called "Hiper". Ma Seok-do goes to the nightclub and interrogates the president where they learn about a yakuza member named Hiroshi supplying Hiper from Incheon in the club. Ma Seok-do's colleagues manages to capture Hiro and seize 20 kilos of Hiper, but a corrupt cop Joo Sung-chul steals Hiper and kills Hiroshi, but Ma Seok-do's team manages to survive the ambush.