Comparing this to Taken, as reviews have, is unfair and will only disappoint, I challenge these comparisons. For me it was more a resemblance of modern BBC TV Detective dramas. The Chaser (a 2010 remake) is slick, deep and packing intelligence, emotion and multi-level story into what is an ex cop enters a serial killers world.
It is shot well, with great South Korean filmography in feel and character. It is deep, engaging, entertaining and well cultured.
The plot involves an ex policeman turned prostitute guardian (pimp). One of his girls goes missing, captured by a twisted customer, who has scared girls before, who turns out to be a serial killer. As the police detain the killer there is a race to find the imprisoned last victim, as she is till alive in an unknown house. More of the killer's character is unravelled, whilst ex-cop Jung-ho has to look after the victim's young daughter, helping to save her mother before it is too late. All of this is shot well in a gritty, but greatly real, Mangwan in Seol at night amongst the streets, back allies and shady homes near the mountains.
If you are into World Cinema and these style of cat and mouse detective dramas, then this film will please fans. I do feel sorry that it suffers from top-billing and raving reviews as a cult gem, when it was for me slick and well produced, rather than being anything special, unique or extra-ordinary. The film is slow, long (2 hours) and thus an asking watch, but a debatably worthwhile one none the less.