First-time writer-director Jae-keun's South Korean action slam is the very definition of Hollywood's "high concept"—including there not being much beneath the glossy surface. Fast-moving entertainment and violence distract viewers from asking deeper questions.
A man emerges from a Seoul car crash with a bullet wound in the arm (there will be a lot of those) and no memory. He is involved in some chase with gangster/secret agent types. But, 12 hours later, when he is in the company of a man without a home (the only person seemingly in sympathy with him and his quest for identity) the hero abruptly finds his whole world shifting. Suddenly he is in the body of another man—apparently one of the threatening types in pursuit.
Before long it is evident that the main character, I-yan (Yoon Kye Sang) was involved in dangerous cloak-and-dagger narcotics intrigues. Twice each day his spirit/soul helplessly migrates into one of the other conspirators involved, now trying to find him. The amnesiac fits the pieces together whilst trying to protect his tough, resilient lover Jin-ah (Lim Ji Yeon) from constant peril from the villains. His efforts are complicated by the fact that, periodically, I-yan pops into the body of one of those same hated villains.
By the third act, a semi-sci-fi/metaphysical explanation is offered over the body switching, but no bigger implications are explored; it is just a gimmick to propel the plot razzle-dazzle forward. Fistfights/gunfights (fistfights with guns, evidently the new martial-arts evolution) predominate, and whilst there is plentiful profanity (material offers both a subtitled and English-dubbed version) and drug references, no nudity/sex is involved.
It is a bit much to see leading lady Lim Ji Yeon perpetually brutalized: her character has practically no reason to exist other than being sadistically threatened. Yes, it might have taken things to a different level if I-yan's mind wound up in Jin-ah's body, but that never happens.
A behind-the-scenes featurette is the main disc extra. If not great art, the action movie Spiritwalker still makes an acceptable, if pure popcorn, addition to international and Asian-leaning film collections in public libraries.