It was the first Hollywood-style big-budget blockbuster to be produced in the new Korean film industry (i.e. after Korea's major economic boom in the late 1990s).

[1] Created as a deliberate homage to the "high-octane" action film made popular by Hollywood through the 1980s, it also contained a story that draws on strong Korean national sentiment to fuel its drama.

[1] Much of the film's visual style is shared with that of Asian action cinema, particularly Hong Kong action cinema such as John Woo, Tsui Hark, Ringo Lam, and the relentless pace of the second unit directors, like Vic Armstrong and Guy Hamilton, in the James Bond films.

Under the auspices of their commander, Park Mu-young (Choi Min-sik), they will be sent into South Korea as sleeper agents, to be reactivated at some later date.

The most promising of the group is Lee Bang-hee, a female sniper who assassinates several key South Korean figures over the next six years.

The agent in charge of her case, Yu Jung-won (Han Suk-kyu) has nightmares about her murdering both him and his partner, Lee Jang-gil (Song Kang-ho).

Jung-won is also engaged to a young woman, Lee Myung-hyun (Yunjin Kim), a former alcoholic and the owner of a fish and aquarium supply store.

Mu-young calls Jung-won and issues an ultimatum: he has concealed several CTX bombs around Seoul, and will give him just enough time to find each one before setting them off.

Jung-won sets a trap by telling Jang-gil he has new information - which Mu-young and his fellow agents step into - but the situation quickly escalates into a firefight, resulting in police and civilian casualties.

He loses her, but notices the light to the aquarium turn on and covertly enters, discovering a bleeding Myung-hyun removing her disguise.

Mu-young confronts Bang-hee about her hesitancy and constant failure to kill Jung-won, reminding her of their primary objective.

Myung-hyun's identity is confirmed by the agency later when electronic surveillance devices are discovered in fish decorating the NIS's office, supplied by her.

The terrorists aim to detonate a CTX bomb directly over the Royal Box, housing all senior North and South Korean politicians, at a soccer stadium in the midst of an international friendly match played between North Korea and South Korea.

A violent confrontation in the control room results in the death of all four terrorists, and the lights are switched off in the nick of time.

[9] The film would later serve as the basis for the television series Iris, starring Lee Byung-hun and Kim Tae-hee.