Question: Who are God Speed You Black Emperor!? Answer: They're a nine-piece ensemble from Montreal, Canada who refuse to be interviewed, issue press releases or publicity shots, remain wilfully non-specific about who plays what on their records, and are singularly wary of allowing outside forces to interfere with their music. So put that in your pipe and toke it.

Slow Riot For New Zero Kanada is GSYBE's second release, following last year's much-lauded album F#a#oo (their third counting the almost impossible to locate cassette debut All Lights Fucked On The Hairy Amp Drooling), and strictly speaking, it's not so much a long-player as an extended EP. However, it deserves consideration on these pages for two reasons: firstly, there's almost 30 minutes of music here, and secondly, given that almost every note of that music is as graceful, slow-mo-violent and majestic as any you'll hear this year, it would be a shame to see it buried in the fortnightly onslaught of singles. Plus, these two Joycean-titled tracks ('Moya', a timeless lament in 3/4 time, and 'Blaise Bailey Finnegan III', a tidal surge of natural dynamics) are both long as life and almost as mystifying.

So, this nonet might currently be the reluctant darlings of the young avant garde, but they steer well clear of the drone zone. The sound is hyper-emotional-bleeding-into-maudlin, trance-like, minimalist and repetitive; Slow Riot could be an isosceles triangle touching on experimental, classical and rock forms, except not as contrived as that sounds. Indeed, if the difficulty of describing a music in print is directly proportional to the quality of content, then this is a minor masterpiece.

Both pieces (instrumental, mostly constructed out of strings, guitar, drums, tape loops, pipes, glockenspiels and source noises) conjure vast, monumental atmospheres: the sound of the Canadian/American land mass slowly dying, skies turning black, the "God help us all" of an anchorman broadcasting news of nuclear war. This is an aural prism where you might catch reflections of My Bloody Valentine, Ennio Morricone, Sonic Youth (circa A Thousand Leaves), the Velvets at their most beautiful, Spiritualized, Mogwai or Philip Glass.

And, no, your reviewer isn't being loose with the dice - Slow Riot . . . is one of the season's landmark releases. Play it between Deserter's Songs and Ocean Songs and judge for yourself.