It is 1985: Detective Chief Inspector Cross of Belfast's Royal Ulster Constabulary is wondering, again, if he should leave the force. He's been there for twelve years, but he's a more adept loner than he is a careerist. He's British and Catholic, neither of which earns him the trust of his Irish-Protestant colleagues, or the civilian contacts essential to his job. And how effective can any officer of the law be in a country grown inured to the facts and effects of decades of violent hostilities?

Still, Cross is unfailingly compelled by murder - the violence almost dazzling in its stark contrast to the "bloodlessness of his own existence," the who and why behind a crime an undeniable driving force in him. Especially at this moment: in a city "where a death was easier to arrange than crossing the road," DCI Cross has spotted the gruesome handiwork of a serial killer.

It might be that Cross has simply stumbled on someone else who's made sectarian violence a vocation, but this killer is cutting across political and religious lines - and with a viciousness reminiscent of a particularly grisly episode in the recent, tortuous history of the city. Cross has to fight his superiors to be allowed to focus attention where he thinks it's necessary, and even when they agree, they handicap him (or so they think) by assigning a young policewoman to the case.

But WPC Westerby is a recent transfer from the sex abuse unit, so there isn't much she hasn't seen; and her keenness, intelligence and ambition make her quickly indispensable to Cross. Because as they close in on the killer, he seems to retreat further and further behind a layered identity and motive. As they uncover more and more about him, they uncover, as well, more and more of the maze of secret, paranoid alliances, backroom deals and sanctioned treachery hidden just below the surface of the conflict.

And even as the situation is growing increasingly clear to them, they are being drawn, perhaps inextricably, into a nightmare world where political and sexual terror form part of the same deadly trap, and where fighting is profitable, people expendable and knowledge of the truth a grave liability.