LET The Right One In is a vampire movie – a simple and obvious statement of fact, which needs to be said up front.

Don’t worry – there’s no hint of a spoiler alert.

It’s just that this particularly accomplished, engrossing and memorable Swedish film seems to be leading something of a double life.

Tomas Alfredson’s picture was praised at film festivals around the world and generated notable buzz before its cinema release in the UK.

But don’t be led astray by the critics and commentators who still seem set on suppressing its true identity.

Let’s say its “daytime” persona is a coming-of-age tale, a story of friendship and loyalty, a blossoming young romance. A tale of a boy gaining the strength to face up to school bullies.

Its “night-time” garb is rather darker – a modern-day entry in the vampire genre that, in its frosty, melancholic, cold-breath-on-a-winter’s-night way, sucks you into its world of white until it chills to the bone.

Let The Right One In is so good, so powerful and so right because it is both vampire movie AND coming-of-age tale – horror picture AND “love story”.

Directed by Alfredson, with a script by John Ajvide Lindqvist from his own novel, it is blessed by two outstanding child performances – Kare Hedebrant as the bullied 12-year-old Oskar who befriends Eli (Lina Leandersson), a girl who moves into his apartment block and tends to roam around at night.

In his recent novel, The Casebook Of Victor Frankenstein, Peter Ackroyd sends the title character to the theatre, and writes of an actor in character: “He was the more vivid for being two people. It was as if he had acquired twice the power of any single human being.”

Being two things at the same time works for Let The Right One In, while young Leandersson pulls off the actor’s trick of being two people, with twice the power of a single entity.

Despite her tender years, she convinces us of Eli’s monstrous longevity, her necessary brutality, her ravenous driving force.

It all ends in blood and tears with a swimming-pool showdown that will have you rushing for the showers.

Let The Right One In is released on DVD and Blu-Ray on August 3.