It's almost a given that if you make a generalised statement about just about anything to do with film, then sooner or later it will turn around and bite you in the neck. Not so long ago I wrote that the vampire genre had some time ago peaked and was now in a state of stuttering decline. It's the inevitable result of a timeline that affects any genre with specific codes and conventions – after a long period of varying the themes set up by the pioneers, revisionism comes along to challenge, rework and even invert these governing rules. Save for the that first rush after genre's birth, this is the single most exciting time in the genre's evolution. For the vampire film it happened back in the 70s and 80s, when independent filmmakers finally turned the back on the genre's literary origins and re-imagined the stories in a modern urban setting or, in the case of George Romero's masterful Martin, turned them completely on their head.

In recent years there have been intermittent attempts to revive the genre with varying degrees of success. None of the new entries have exactly set the screen alight and all have played very much to formula, riding a wave of new convention that arose after independent revisionism gave way to studio cash-in. With such re-invention now a thing of the past, it seems likely that all we really have to look forward to are small variations on increasingly familiar characters, stories and themes, and this late in the day there's just nowhere fresh to go with that, is there. Is there? Cue Let the Right One In [Låt den rätte komma in], a Swedish vampire tale that abides by genre conventions but is still quite unlike any vampire movie you're likely to have seen.

As the film begins, early character moments that only make sense in retrospect or on a second viewing give way to dark intrigue, as a middle aged man calmly assembles a collection of tattered paraphernalia and then grabs and drugs a young man in a snow-covered park, hauls him up to a tree branch by his feet and slits his throat, collecting his blood in the sort of plastic container you'd buy a bulk supply of washing-up liquid in. When the process is disturbed by a couple walking their dog, he flees the scene, forgetting in his haste to take the blood with him.

Back home he is balled out for his stupidity by an unidentified female figure, but we can guess who she is because we've met her already when she said a quiet hello to Oskar, a withdrawn 12-year-old boy of fair complexion who is practicing knife thrusts on a tree in the courtyard of his apartment block. The girl's name is Eli, she's about Oskar's age, and she and her father have just moved in next door. Oskar wants to be friends, but she doesn't seem too sure. And Oskar really is in need of a friend – those practice knife moves are a wishful response to the daily bullying he suffers at school from a boy named Conny and his two cronies. Whether he needs a friend like Eli is, at this juncture, open to question.

We can presume from his unruffled approach to his victims that Eli's father, if indeed he is her father, has been procuring blood for her for some time, but his luck is starting to falter. Having been interrupted in the park, his second attempt goes pear-shaped when the victim unexpectedly wakes from his drug-induced unconsciousness and loudly alerts his friends to his location and his unhappy, upside-down state. Too weary to flee, Dad takes drastic action, not against his angry pursuers but himself. A final act of devotion (or obedience) to Eli temporarily eases her craving, but deprived of her delivered-to-the-door blood supply, she soon takes to the streets and attacks one of the locals. The assault is witnessed from a distance, and in this small and insular urban community, fear and anger soon begin to spread.

While the basics of the plot may be walking a recognisable generic path, the handling is a different story altogether. Take that early park abduction and blood-letting, the perfect opportunity for a gory make-up effect in horrible close-up, but the throat cutting is hidden from view and much of the scene is shot wide. Indeed, there are a lot of such shots in the film, more than you might be used to seeing in a vampire movie. Many of the film's pivotal moments are filmed this way, precision composed scope wides that have a coolly observational quality, the antithesis of the frenzied close-up waggle-cam of 30 Days of Night and its contemporary brethren. Not only does this make the film stand out stylistically from the crowd, it brings an unexpected subtlety to aspects that are usually showcased front and centre. Such an approach reinvigorates elements that over-usage has rendered almost de rigeur rather than crucial to character or story, and in the process something rather wonderful happens – for the first time in I can't remember how long, they become genuinely unsettling. A good example occurs when Eli scales the side of a tall building, a move genre fans will certainly anticipate but that takes place in the background of a wide shot that we have been misdirected to believe has a different purpose. The sudden, corner-of-the-eye realisation of what is happening produces the sort of shudder you get when you're watching TV and just catch glimpse a large spider as it disappears under the sofa.

It's no distortion to suggest that for much of the time Let the Right One In doesn't play like a vampire movie at all, at least in the commonly accepted sense, to the extent that if you removed the generic element then you'd still have an intriguing and sensitively handled story of awakening friendship and social isolation. It is a vampire tale, of course, but by not making this the element around which everything else rotates and by integrating it so successfully into a substantial drama, it becomes a key element in a larger and more complex picture of community, family life and the pains and desires of growing up.

The heart of the film lies in the developing relationship between Oskar and Eli, and it's typical of Swedish cinema that a coming-of-age-drama can be so successfully built around a couple in their early teens and feel truthful and touching without ever straying into morally problematic territory. Even a moment when post-attack Eli strips and climbs into bed with Oskar – who is genuinely surprised by her actions – comes across as tender rather than erotic, a search for human warmth rather than sexual contact from someone who is otherwise isolated by her condition. It's also typical of the underlying maturity of both characters that after the initial shock, Oskar accepts her for what she is. "Are you a vampire?" he asks calmly as the two are separated by a glass door panel, a barrier imposed by Eli herself until sure of Oskar's acceptance.

As with the best of modern vampire movies, Let the Right One In credits the audience with a knowledge of genre rules that it abides by but rarely needs to explain. Thus we know why Eli gets agitated and facially hollow when denied the blood she needs, why her father's first job on moving in is to tape up the windows to the apartment, and why surviving a vampire attack might leave a victim reactive to sunlight. Even the title is a play on one of the less well-known aspects of vampire lore, that a vampire can only enter a home if invited to do so, something never fully explained here and whose bloody consequences if ignored are used not as a battle tactic, but by Eli as a potentially suicidal plea for Oskar's understanding and friendship.

There's commendable subtlety in the handling of so much of this, with Eli real age and collected wisdom suggested simply by the speed with which she is able to solve a Rubik's cube, her imperviousness to cold by her flimsy outdoor clothing, and her enhanced physical abilities by sleight-of-hand editing rather than look-at-me CG effects. The conversations between the young couple are gentle and unhurried and take place in isolation, even when outside, on streets whose eerie emptiness is the result of sub-zero temperatures rather than a community hiding fearfully behind closed doors. And although the final scene may play to audience expectations rather than with them, it's handled with such electrifying originality that I can't see anyone finding cause for complaint.

Let the Right One In doesn't reinvent the genre in the manner of George Romero's seminal Martin and in many ways plays by the traditionalist book. But in looking at familiar elements with fresh and adventurous eyes and planting them in such a strong dramatic base, novel author and screenwriter John Ajvide Lindqvist and director Tomas Alfredson make it all feel new, as if this was the first great work in an only recently born genre. And a great work it is, for its sympathetic and believable characters and its gripping drama, for its fine performances and its perceptive and truthful look at childhood, for its unhurried pacing and sometimes haunting stillness, and for a subtextual richness that I've barely touched on here. I've perhaps seen too many vampire movies and forged too deep a relationship with the genre to go with the Washington Examiner claim on the Blu-ray box (one my girlfriend aggress with, I should point out) that this is the best vampire movie ever, but this is still a marvellously realised work in which the generic elements are a crucial component rather than the dominating factor, and is, without question, the most thoughtful, original and satisfying vampire movie to hit the screens in over thirty years.

Although not one of those discs you'll be pulling off the shelf to show your standard definition friends just how amazing the picture quality on Blu-ray can be, the 2.35:1 transfer here should still easily outstrip any DVD release we're likely to see. Detail and sharpness are as crisp as you'd expect of a BD release of an even modestly budgeted modern film, with consistently good contrast and no picture information not lost to either the shadows in the darker scenes or the white in the daytime snow. Indeed, there's a vibrant look to some of the night-time exteriors, while the slightly muted colour scheme feels right for the film's tone and the often overcast skies of the location (in the accompanying featurette the director himself describes the colour scheme as "very Swedish"). In the rare shots where the sun does shine the HD picture really shows its superiority over DVD, particularly in clothing and architectural detail.

You can choose between Swedish or English 5.1 DTS-HD Master Audio soundtracks, the English being a dub for the subtitle-phobic, and while it's not as bad as some it's still all wrong for the film. Even run through a non-HD DTS amp, the clarity, separation and dynamic range of both soundtracks is excellent, with a pin-sharp crispness to every sound effect, a rich fullness to the score and some serious bass rumbles when either the music or effects hit the lower frequencies.

Deleted Scenes (5:52)
Four deleted scenes in Swedish with fixed subs that cover another incident of bullying by Conny, some further friendship building between Oskar and Eli, the reaction a bite survivor when she tries to drink a glass of wine, and a further scene between Oskar and Eli in which conflict dissolves into mutual understanding.

Behind the Scenes (7:37)
This looks like an EPK for the film's release outside of its home country, with director Tomas Alfredson outlining in English the Sweden of the film's period setting of 1982 for those of us not clued into the significance of that (you can include me in that group) and briefly discussing the casting of the young characters and some other aspects of the film. There's some interesting behind-the-scenes footage, but be warned that the final scene is covered in some detail, so watch after the main feature.

Also included and of less interest is a Photo Gallery containing 18 promotional stills and a Theatrical Poster Gallery, which has 5 not too varied posters.

Let the Right One In is a film that arrived here with a considerable reputation to live up to and manages the rare trick of doing just that. Those who like their vampire movies loud and fast and by the generic numbers may want to wait for the inevitable 30 Days of Night sequel, but for the rest of us this is the film that I, for one, never thought would happen, one that reinvigorates a genre that I was convinced was in terminal decline. Whether this is a one-off or the opening salvo of a new wave will be interesting to see, but it's going to be damned difficult to top, with only Park Chan-wook's Thirst [Bakjwi] looking set to offer any real competition for the moment. And yes, Hollywood is already planning to bugger it up with a doubtless inferior remake, so see the original and encourage others to do likewise. If you can't get to one of the few UK cinemas at which it's playing and can't wait for the UK DVD release (I certainly couldn't), then this region-free Blu-ray offers a very decent alternative, despite being thin on special features.