Ji-won is a North Korean resident spy and begins a mission to assassinate a traitor. Hot-tempered South Korean intelligence agent Han-kyu gets to know such plot and attempts to arrest him but fails. As a result Han-kyu resigns from the agency. 6 years later, Han-kyu opens an investigation agency and comes across Ji-won once again. Wanting the bounty for bringing in Ji-won, Han-kyu offers him a partnership to keep him close.