Imagine this: Japan invades Korea in early 1900s. Japan allies itself with America to defeat Germany in WW2. Korea loses its identity and becomes a state of Japan. Japan joins the UN in 1960. In 1988 Japan hosts the Olympic Games and the World Cup in 2002.

Notice anything different? To the characters in 2009 Lost Memories, this is their version of history. Japan rules over Korea and Koreans have suffered this humiliation for many decades. Yet it is history and nothing or no-one can change it, or can they?

This is the basis of the story in this big budget Korean flick. Someone had travelled back in time to prevent the assassination of the Japanese governor of Chosun (Korea) in 1909, thus changing the whole course of East Asia's history.

Sakamoto Masao is Korean and also a member of the JBI (Japanese Bureau of Investigation) with Saigo Shojiro as his friend and partner. Together they have solved a good number of cases together, including the recent attack on a museum by the terrorist group Hureisenjin. However, it seems there is more than meets the eye about the activities of Hureisenjin, and Sakamoto wants to know why there is a mysterious relationship between the powerful Inoue Foundation and the terrorist group.

His investigations lead him to discovering the true intentions of Hureisenjin and their continuing battle against Japanese authorities to regain their lost country. When he himself is betrayed by the JBI he sides with Hureisenjin after they tell him about the alternate history line - the true history line (The successful assassination attempt; Japan loses WW2; Korea is divided into North and South Korea, and their reunification sixty years later).

Sakamoto must then use the Lunar Soul - the key to opening up the time portal, so that he can travel back in time to stop a Japanese man called Inoue from preventing the assassination attempt. But Saigo has also been told of the alternate history and his job is to travel back to stop his friend Sakamoto from rewriting his own history.

If this sounds all complicated, it isn't, but the temporal plotlines are full of holes when you think about it. This doesn't stop the film from being a lot of fun, and although there are a lot of preachy parts, the great action sequences are worth it alone. Characterisations are aplenty but the script is full of cliches. By making the terrorist group a fearsome entity, audiences obviously side with the JBI at the beginning of the film, but as the film gradually folds, the audiences switches side with Sakamoto and becomes sympathetic to their cause.

2009 Lost Memories was a huge hit in Korea because of the huge action setpieces and the gung-ho wave the flag "let's get patriotic" feeling. The first half of the film is very entertaining, but I felt the last half tried to do too much, and the time travelling aspect of the film was poorly designed and executed. The mexican stand-off right at the end was another cliché but great drama nonetheless. This is a film more about Korea's sensibilities, but the rest of us can be assured of an entertaining time. The alternate history story is a good touch, but the last quarter of the film could've done with a bit more polishing.

They should remake this film in Hollywood - about the allies losing WW2 when someone travels back in time to assassinate Churchill and Roosevelt. Great Britain becomes another state of Greater Germany, Russia licks its wounds after conceding masses of land to Hitler, and the USA retreats back to its own continent, besieged by the massive power hierachy of Germany and Japan. Unravel that.