Holes permeate the work of extraordinary Japanese novelist Hauraki Murakami. Like the well down which our hero descends in existential crisis in The Wind-Up Bird Chronicle, or the apocryphal pit lurking menacingly throughout the opening of his breakthrough, Norwegian Wood. And then there are the dark caverns beneath Tokyo in Hard Boiled Wonderland and The End of the World. Murakami understandably references that last himself in this, his first stab at book-length non-fiction: terror and uncertainty below ground; underground.

Early on Monday 20 March 1995, five senior members of the Aum Shinrikyo ('Supreme Truth') cult, under instruction from leader Shoko Asahara, introduced the deadly nerve agent sarin into the Tokyo subway. In the ensuing confusion 12 passengers and staff died, thousands were badly injured.

In the years immediately following Norwegian Wood, Murakami lived in self-imposed American exile. On the morning of the attack, however, he was back at his home outside of Tokyo, albeit without benefit of TV or radio. A friend called, advising him not to go in that day and, by his own admission, he gave events little further thought.

As the scale of the disaster unfolded, however, the novelist's interest peaked. Underground is his response - a meticulous reconstruction through interview, a testament to the silent majority and an author's probing of the Japanese psyche. Through his researches Murakami attempts to find a way to reconnect to an ostensibly foreign country: '[I] was able to see what it meant to be Japanese when confronted by a major shock like the gas attack,' he writes.

The interviews prove moving and engrossing in isolation, but it's only gradually that their purpose is revealed. Like Geoff Ryman's fictional 253, set aboard a London Tube train, Murakami's book both bears witness to and seeks to impose narrative upon arbitrariness - cumulatively, continually reversing time, leading more blind travellers inexorably into the unfolding horror. Again and again we see characters from different perspectives, in the sure and certain knowledge of their impending demise. Murakami's own short introductions become progressively less impersonal. 'Words can be practically useless at times, but as a writer they're all I have,' he says.

Less successful is the final third (originally published separately as The Place That Was Promised) wherein Murakami returns to interview Aum members past and present. 'In Underground,' he says, 'Aum Shinrikyo was like some unidentified threat - a 'black box' if you will.' Unfortunately, while Aum 'shows us a distorted image of ourselves,' the cultists themselves are staggeringly banal - bright, dissatisfied, impressionable youngsters prey to Asahara's perverse strand of apocalyptic Buddhism. (With its money-grabbing and rigid hierarchies, Aum comes across like the paramilitary wing of Scientology.) Its attraction, as so often with religions both freakish and prosaic, eludes all but the most deluded. Which, in its way, of course, makes Murakami's tale all the more heartbreaking.