In February 2000, 58-year-old Albert McFarland, a civilian employee of the US military based in the South Korean capital of Seoul, was accused of ordering a Korean subordinate to dump 24 gallons of formaldehyde into the Han River, the prime source of drinking water for the city's twelve million inhabitants. The case prompted local outrage and anti-American protests calling for the withdrawal of American troops. The US military maintained that the chemical posed no threat to public health, but environmentalists insisted that the chemical was potentially cancer-producing and deadly to marine life. If director Bong Joon-ho's latest film is anything to go by, it may have been responsible for something else entirely.

The Host (Gwoemul) kicks off with a virtual recreation of the McFarland incident, which acts as both a pointer to one the film's underlying themes (there are several) and a prologue whose consequences we are introduced to disarmingly early in the narrative. Bong leaves it to us to connect the two incidents, relying on our knowledge of horror film history and our concerns about the effects of pesticides, chemical waste and genetic engineering to fill a narrative gap that would once have been provided by spectacled scientific characters with suppositions about terrible mutation. Yes, The Host is a monster movie, a GREAT monster movie. But it's also a whole lot more.

The first three members of the family at the film's core, the Parks, are broadly but very effectively sketched in a matter of minutes. Elderly Hie-bong (Byeon Hie-bong) runs a small food stall located on the bank of the Han River, assisted by his lethargic, 30-something son Gang-du (Song Kang-ho), whose wife has long since departed, leaving him with their only daughter Hyuen-seu (Bae Du-na). Although devoted to Hyuen-seu, Gang-du is otherwise given to incompetence and falling asleep for extended periods, often when on duty at the stall, a trait wonderfully established when his father arrives on the scene in time to conduct a sale and has to lift his son's sleeping head off the counter and peel the change from his cheek. Sent down to the riverside to deliver complimentary food and drink to customers whose food he had picked at, Gang-du finds a crowd fascinated by something they can see dangling from the nearby bridge that then drops into the river. Is it a marine animal? Gang-du tosses a can of drink into the water and it is quickly pulled under. The others follow suit. This time the creature ignores the offered snacks and instead leaps out of the river and goes after the general public.

Even by the let's-get-down-to-it approach of more recent Hollywood works such as War of the Worlds, The Host is surprisingly quick out of the starting gate, its monster unleashed and in full view just minutes into the main story. But Bong is not doing this to show off his creature, his relentlessly mobile camera aligning itself instead with the fleeing Gang-du and his terrified compatriots, the creature appearing and disappearing as it leaps into their line of sight, slips and falls down a bank or, in a particularly neat bit of compositing, is observed though the window of a passing train. When Hyuen-seu emerges unknowingly from watching her sister on TV, Gang-du grabs her hand and attempts to drag her to safety, but in the panic loses her grasp, realising his mistake just too late to save her from being scooped up by the creature and pulled down into the river.

At the mass funeral for those killed by the creature, Gang-du is re-united with his sister Nam-joo, a national archery medallist who froze at a crucial moment in a recent competition, and brother Nam-il, a grumpy college graduate in search of a job and a purpose to his life. When it is revealed by the authorities that the creature is actually a host for a SARS-like infection, the entire family are quarantined. They've not been in hospital long when Gang-du gets a phone call that reveals his daughter is still alive, and the Parks become determined to find and rescue her from the sewer in which she and others are being ominously stored.

Now I should state up front that the title creature is a CGI creation, and although wonderfully designed and animated it does for the most part look like one in the way that such effects just tend to do. But I'm prepared to swallow a lot if the surrounding meat is more than just set-dressing, and that's certainly the case here. The creature itself is a fascinating beast, part Bruce the shark, part Predator, part Tremors sand worm, and with the speed and agility on land of an angry but overweight velociraptor crossed with an Olympic gymnast. It certainly proves solid enough to present a tangible threat and, later in the story, deliver a couple of world class jolts – this may be the first time CGI has actually made me seriously jump. Unlike films in which the monster is the sole draw, the drama is so involving and characters are so well drawn (most of the main cast were equally compelling in Bong's equally excellent Memories of Murder) that rather than look forward to the beast's next appearance you actually come to dread it. Inevitably the creature has allegorical status, from the obvious warnings of the consequences of industrial pollution to a symbol of Korea's underclass – in a narrative sidestep that is very neatly dovetailed back into the main story, a poor man takes his young son on a food raid and justifies their actions  by telling the boy of so-rei, a right of the hungry. Seconds later the pair are confronted the creature, created by the folly of man and now exercising its own form of so-rei.

Humour is used both for character engagement and as part of the film's varied emotional tapestry, which Bong weaves through with unblinking confidence, allowing the tragic to evolve into the comedic in the space of a few short seconds (the initially sad funeral that dissolves into hilariously overwrought histrionics is particularly good example). There are even gags placed purely for genre fans to savour – Bong clearly knows his horror movies and at times appears to lining up the clichés purely to shoot them down. Thus a girl who is locked out of a seemingly safe haven when the monster attacks is not eaten as expected, but the only one spared when the creature bypasses her and ploughs into the shelter, and a military official who switches on the TV for one of those news broadcasts that always seem to be playing when exposition is needed is unable to find one on any channel, despite a frustrated search.

That's not to say familiar elements are excluded, but when they do appear they are organic to the narrative, often on more than one level. Where western horror films, for instance, repeatedly recycle the same contrivance for robbing characters to be isolated of their ever-present mobile phones (no signal, somebody smashes it), Bong incorporates this into both the plot and the subtext. Young Hyuen-seu doesn't have a phone simply because her hard-up father can't yet afford to buy her one, and the bucket of coins he has saved for this very purpose is eventually used instead to bribe an official. (Further layering is provided when Gang-du uses his own phone as a representation of his daughter when trying to explain to disinterested officials how she could have survived being grabbed by the monster.) Even the main characters initially fall wide of expectations – effecting an escape from the hospital and tooling up to search of the monster's lair, their lowly funds leave them short of equipment and they realise they have no idea where to look. They search fruitlessly until they are individually incapacitated by a combination of bad luck and poor foresight, the sheer size of the Seoul sewer system surprising them in a way that, with a little reasoning, it should not have.

The Host delivers in a way few monster movies since the golden days of 1950s Hollywood genre works have done. In its deft blending of horror, comedy and personal drama with a strong socio-political and cultural subtext it's considerably more sophisticated and satisfying than most, and I've only touched on wealth of character and allegorical detail that pack this remarkable film. There's no two ways about it – The Host is, quite simply, an absolute belter, as smart as it is entertaining, and easily the best monster movie to emerge from anywhere since Alien.

Framed 1.78:1 and anamorphically enhanced, this is a pin-sharp transfer with excellent contrast and colour reproduction, given the minor games played with the colour palette that are almost expected in modern genre works. Black levels are perfect and compression artefacts rare. One advantage of being a film-only disc is that the bitrate is consistent high, often peaking at maximum.

The Korean DTS 5.1 track is and well mixed, the surrounds well used for location atmospherics and there is some effective separation of voices, sound effects and music. The bass kicks when it needs to, notably the creature's footsteps and the drumbeats of the score. An excellent track. The 5.1 is not quite as lively, but still very effective if you crank the volume up a bit. A Cantonese stereo 2.0 dub has also been included.

The English subtitles have no obvious spelling or grammar issues, though are Americanised – the coins in Gang-du's pot are described as "quarters and dimes," a currency I was not aware Korea used (but who knows, maybe this is the correct translation of another sly comment about stationed American servivemen.) The subtitles appear on all of the dialogue, including lines delivered in English.

Not a thing – you only get the movie on this disc.

A knockout movie that looks and sounds great on this Hong Kong region 3 DVD from CN Entertainment, the only down side being the complete lack of extras. The film's huge success in Korea and other Far Eastern territories has ensured that there are already a number of DVD releases available (I've counted six so far), including KD Media's 'Limited Complete Edition', a 4-disc set that includes three commentaries, a lorry-load of extra features and the soundtrack CD, though it seems unlikely the extras will be subtitled in English. CN Entertainment's release is at the other end of the scale, a lot cheaper but devoid of supplementary material. Possibly the best compromise for UK viewers not fluent in Korean is Optimum's upcoming 2-disc region 2 release, which includes its own impressive collection of extras that will be subtitled in English. The only question unanswered at present is how the picture and sound will match up, something we will be covering when it appears. If you're not bothered about extra features and have a multi-region player, then CN Entertainment's DVD can be found at about half what you'll pay for the Optimum disc, and in that respect is good value.