Jamie Stewart is standing in your hallway with a knife in his neck, cutting his own head off. I know what you were thinking when you opened that front door: "Oh, that nice Xiu Xiu man's here with his new record!"  So you let him in, didn't you? Popped the kettle on and hoped for a chat. And now the detached head of Jamie Stewart is lolling about on your new carpet, and you have no idea how to respond. It's singing a song called 'Black Dick', whose key hook is the strangled repetition of the word 'dick' over a four quid breakbeat and a squall of synths that sound like they hate each other. Good going.

I know you felt a bit safer around Xiu Xiu in recent years. I saw the way you danced nervously in your kitchen to 'Chocolate Makes You Happy', how you lit those scented candles and had a good cry to 'The Oldness'. You felt that Jamie was growing up with you, letting a little light in, getting five stars in the Independent. But that nuclear-winter howl opening up 'Angel Guts' isn't your mate, is it? Those bird-of-prey squawks hovering over your head on 'Lawrence Liquors' aren't there to make you feel all warm and fuzzy inside. 'EL Naco's wedding bells don't seem to be giving way to a poignant reflection on ageing that we can all take to heart, only discordant drones that pin you to the bed. 'Cynthia's Unisex' is not going to lend itself to your next ukelele-only open mic night.

There is a little let up: 'Bitter Melon' gives you a few minutes off with warm pads and a camp, knowingly out-of-place calypso beat. It marks the only track on the record where Stewart really allows himself to sound pretty, where he briefly stops dredging the lake for bodies. And it's almost immediately cut to shreds by the funereal 'A Knife In The Sun'. You might even have a go at tapping your foot quite nicely to 'Stupid In The Dark's chorus, or let the big-drum march of 'Botanica de Los Angeles', with its drowned-at-birth guitar solo, slowly seep under your skin if you let it. But it'll only end in tears.

Angel Guts: Red Classroom is a reaction of a record that demands you stop enjoying Xiu Xiu, this instant. Like a couple of art-hounds happily guzzling Merlot in the shadow of a Francis Bacon triptych, a decade of exposure to Stewart's work can leave you almost numb to it. You become familiar with the horror, expect to feel uncomfortable, familiarise yourself with the artists' moves at a safe distance. And it's been made easier as the records themselves have become more accomplished.

'Angel Guts' operates a scorched-earth policy, reliant on little more than analog synths, outmoded drum machines and Stewart's voice at its most discomforting, his lyrics at their least sympathetic. This is a deliberate Difficult Listen, an Atrocity Exhibition, an Intense Humming Of Evil. If you've always been a Stewart-skeptic, there's a good chance you'll dismiss this as Super Hans conjuring a powerful sense of dread; if not, it's likely to genuinely unsettle.