After bringing down a dangerous drug cartel, detective Won-ho thought he could finally have a peaceful life. However, when a mysterious figure called "Doctor" emerges with a new lethal drug called "Felix", Won-ho realizes his job is not over. As bodies pile up from the new drug, Won-ho launches an investigation to track down Doctor and dismantle his organization.He discovers that Doctor was a former chemist working for the previous cartel Won-ho took down. After that cartel crumbled, Doctor went rogue and decided to take over the drug trade himself with his innovative new drug Felix. Producing the drug requires rare chemicals that Doctor illegally imports using a complex network of overseas connections.As Won-ho and his team start closing in, Doctor becomes increasingly paranoid and violent. A bloody trail leads Won-ho deep into Seoul's criminal underworld where he uncovers more about Doctor's background as a reclusive, vengeance-driven genius. After many dangerous run-ins, Won-ho finally locates Doctor's secret lab and prepares for a dramatic final confrontation to stop Felix for good. With his family's safety on the line, Won-ho knows he must risk everything to hunt down this dangerously brilliant mastermind.
