Man in the Dark, By Paul Auster

Paul Auster has done many courageous things. He has made a living as a novelist while holding steadfastly to the belief that fiction is "magnificently useless". He has been lauded by Derridean dons and Lacanian lackeys for his post-modern tricksiness – and refused to change tack. He has sung an obituary with a lo-fi, avant garde, Finnish band called The Farangs. (Me neither.) But such braveries are as nothing when set against Auster's latest fearless act. He has written a novel about... a guy who reviews books.

The man in question is August Brill, ageing, recently widowed, unsteady on his feet and "alone in the dark, turning the world around in my head as I struggle through another bout of insomnia". To help him make it through the night, August tells himself a story about Owen Brick, a Brooklyn children's magician who wakes up one morning in a war zone. Following a disputed presidential election, several states have said they are devolving from the union, and President Bush has declared war.

Sounds fantastical? Well get a load of Brick's task, which is, a superior officer informs him, to assassinate the man responsible for all this chaos. No, not Dubya, but that dastardly book critic Brill, because "he owns the war. He invented it, and everything that happens or is about to happen is in his head. Eliminate that head, and the war stops. It's that simple." I love the confidence of that last order – less military bark than barking mad. Unfair, perhaps, to expect a sergeant in the US army to be up to speed on self-reflexive narratology, but even Captain Mainwaring could see that doing away with the chap who's writing your lines will likely do you no favours.

So far, so Austeresque, but then things begin to work the other way round. Brill might not actually finish his soldiers off but he does finish with them: two-thirds of the way through the novel he switches focus from fantasy to real-life – the life he shares with his middle-aged daughter Miriam, "who has slept alone for five years", and her 23-year-old daughter Katya, who has slept alone ever since her boyfriend Titus took himself off to Iraq where he was beheaded by terrorists who put video footage of their slaughters on the web.

If that sounds like a downer, all I can say is that you close Man in the Dark feeling sunny enough. As Brill comforts Katya by telling her how he courted her grandmother, how they parted and came back together, how he misses her more than he could have ever thought possible, Auster summons and sustains a heartfelt tone utterly new to – and yet of a piece with – the more abstract aspects of his story-telling. After a dozen novels one is used to watching him break new ground. This time Paul Auster breaks your heart too.