By JOHN McCRYSTAL*

From the opening line, you know that this novel is going to cross out of your comfort zone: "They were walking along the river path, away from the city, and as far as they knew they were alone." That phrase, "as far as they knew," just keeps on resonating.

Tom Seymour is a middle-aged forensic psychiatrist whose childless marriage is falling apart. He rescues a youth who throws himself into the river with the clear intention of committing suicide, and subsequently recognises him as Danny Miller. Tom had dealings with Danny several years before when, as a 10-year-old, Danny had murdered an elderly neighbour. Tom's evidence was instrumental in having Danny found fit to be tried in an adult court and imprisoned.

Is it by accident or design that Danny is back in Tom's life? Does he ask to explore the murder in a series of sessions with Tom in order to exorcise or exercise his demons? Why does Tom agree to do it, and persist even when it seems that he may be doing more harm than good? And is Martha Pitt, Danny's probation officer and a close friend of Tom's, just one of the many who have found themselves over-involved in Danny's case?

Many readers will be familiar with Pat Barker's terrific Regeneration trilogy of novels which deal with fictionalised encounters between psychologist William Rivers and poet Siegfried Sassoon during the First World War. One of these, The Ghost Road, won the 1995 Booker Prize. I hadn't read her most recent book, Another World, and found that there was a problem adjusting directly from the trilogy to Border Crossing in that Rivers, so to speak, ran through it: the cool, detached Tom is strongly reminiscent of the cool, detached Rivers. The difficulty was temporary, however, and will be no obstacle to anyone who comes to Barker for the first time in Border Crossing.

One of the things Barker does so exceptionally well is present the complexities and inscrutability of human motivation. The issues are as foggy as the dim air of Newcastle, where the novel is set, as chilly and murky as the water from which Tom drags Danny. Words like "right" and "evil" have no purchase. We are given no insight into Danny's real nature, and only a little more into Tom's. In the absence of certainties, a nagging sense of unease pervades, even as there are subtle clues that redemption is possible, such as Tom's glimpse of a rare pair of otters, which he at first mistakes for rats, frolicking in the filthy waters of the Tyne.

At its best, Border Crossing is a perfect evocation of that perverse part of us which draws us to danger and to dangerous characters - fictional and real - like moths to a candle, and which makes the line that separates us from them so thin.

Anyone who enjoyed the television series Cracker, or the unsettling psychological novels of Ian McEwan, or even just a swim at a west coast beach in big surf, will love Border Crossing.

Penguin

$34.95

* John McCrystal is an Auckland freelance writer.