The Third District.

Unicorn, though a respectable corporation, is actually a shady organization that collaborates internationally in drug trafficking and assassinations. Its heir apparent, Ki-cheol, and his loyal ally, Cheol-ho, are among its leaders. Meanwhile, detective Min-gyu, the head of the detective unit, single-handedly works to uncover the organization's dark secrets, but is brutally murdered along with his wife by those who have even recruited the Interpol director.