Once Upon a Time was the first major investment by SK Telecom's film division, established late 2007, and was released in South Korea on January 30, 2008, under the company's CH Entertainment banner.

Kanemura is a well-connected con artist who makes money by selling ancient Korean artifacts to wealthy Japanese collectors.

After a twenty-year search, the Japanese Chief of State—a high-ranking official in Korea—has recovered the "Light of the East", a 3,000 carats (600 g) diamond and lost treasure from the ancient kingdom of Silla.

But the nightclub owner and his chef are also at the party, and their bungled assassination attempt on the Chief of State results in a fire, allowing Kanemura to slip away in the confusion.

She refuses to hand over the diamond, but he has planted explosives on the railway track, and, having cut off her escape route, succeeds in dragging her back to Seoul.

Suzimura and his other police officers soon follow, but he misreads the situation; believing Hasekawa to be a traitor who has taken Japanese soldiers captive, he orders his men to shoot him.

[10] Yang Sung-jin of The Korea Herald commended the "solid performances of the leading characters," while also giving credit to the comic relief provided by supporting actors Sung Dong-il and Jo Hee-bong.

"[12] James Mudge of BeyondHollywood.com regarded Jeong's direction as being "slick and confident throughout," and commented that while the film lacked originality, "it stands as a solid, entertaining action comedy that should be enjoyed by all.