Once

Herald rating: * * * * *

Cast: Glen Hansard, Marketa Irglova
Director: John Carney Running time: 85 mins
Rating: M, contains offensive language
Screening: Academy, Berkeley Botany Downs, Bridgeway, Rialto Hamilton
Verdict: The certain hit of the summer is a small, smart and utterly charming love story - with great tunes

Make a note: this is the film everyone will be talking about - and seeing repeatedly - this summer. Clocking in at less than an hour and a half, it's a small and perfectly formed gem that will leave you glowing for days.

I'm scared to say how good it really is for fear of overselling it; it's such a tiny, fragile thing and, on paper, sounds so improbable. But the unaffected charm of its two main characters, neither of whom is named, gets utterly under your skin.

One is played by Hansard, lead singer of the Frames, who opened for Bob Dylan during his last tour (writer-director Carney is a former member of the same band). Newly dumped by the love of his life, he's a songwriter and busker (with a guitar so battered the top is worn through) whose specialty is the heartsore ballad which he, usually ignored, wails on the streets of Dublin. He's accosted by a woman (Irglova), an indigent Czech immigrant with her own heartaches, who indulges her musical passions by playing the pianos in the showroom of a indulgent music dealer.

The love story that develops is anything but predictable, both in its arc and its outcome, but it gives nothing away to say that it's a musical romance. The early scene in which he teaches her one of his songs is one of the most dizzyingly romantic ever filmed, and what evolves is an entirely new take on the movie musical in which the music is not some sort of artificial interlude but part of - one might say all of - the story.

You've seen Hansard before - he was the beanie-topped, ginger-haired guitarist in Alan Parker's The Commitments, which had much of this film's appeal. But Carney's decision to cast him instead of a name star (Cillian Murphy was considered) is a stroke of genius. His mixture of tentativeness and aggression is deliciously specific and newcomer Irglova, only 17 when the film was made, is a revelation.

It warrants a profanity alert, but the words ring true in the characters' hardscrabble lives and it never feels gratuitous. If it doesn't tow your heart away, it may be worth checking you still have one.