Hell, a character observes near the end of this British spy novel, is not some far distant region. "It was a millimetre away, and all one had to do was scratch at the surface with one's fingernail to reveal it."

For 20 years, English mystery writer Ian Rankin has scratched that surface with hardheaded police inspector John Rebus as his guide and the gritty environs of Edinburgh, Scotland, as his landscape of not-so-apparent dangers.

To date, Rankin has featured Rebus in 18 novels, which share dark themes, emotional and physical violence, oceans of pints being downed and labyrinthine plots that require close reading to unravel.

Rebus, with his drinking, fractured relations with other officers and ties to the underworld he's trying to police, is like that slightly overweight kid on the playground who naturally draws bullies and tormentors.

Like that kid, he is battered, kicked and abused. But he always manages, sometimes with eyes swelling shut, to fight back, swinging his arms until, by a dark miracle, he manages to connect. More often than not, he's alone on the playground at the end, a survivor, the troublemakers on the run — or worse.

Rankin's volumes are not beach books to be skimmed but midnight books to be chewed and slowly swallowed. Though the novels can be tough going, the rewards are great: One of his books, "The Falls," is one of the best detective works of the new century.

Though Rankin is best known for Rebus, he occasionally ventures out of Edinburgh and police work and into the land of spy thrillers. One of those forays is "Watchman," published in 1988 after the success of Rankin's first Rebus book, "Knots and Crosses," and now being published in the United States for the first time.

Miles Flint is a spy with the British secret service — a watchman — his job to undertake surveillance and report back the results. Simple enough, except that he's been making mistakes and they're getting worse.

As he tries to avoid a complicated home life one night, he unexpectedly joins colleagues on what seems to be a straightforward surveillance job. Thanks to his slip-up, disaster strikes and his superiors are suddenly breathing down his neck.

He suspects that something is up and starts to hunt for clues within the department. That draws unwanted attention and before long he's sent to Belfast, Northern Ireland, on an assignment that's not at all what it seems.

The book takes place mainly in London, a city then as now on edge from a terrorist bombing campaign. In this era of Islamic militants targeting civilians on buses and the underground, it's easy to forget that not that long ago another brand of homegrown fanatics, the IRA, were taking innocent lives in the name of a cause.

Characters jump into restaurants to find a phone instead of pulling out a "mobile" to make a call, but otherwise the book is fresh, as though written yesterday and not two decades ago.

Unlike Rebus, Flint is an amateur student of beetles, married, though not happily, and the father of a grown son. He's a little quicker on his feet, a little less prone to self-destructive habits. But in more ways than not, the men are different sketches of the same character.

They're independent in their personal and professional lives. They're deeply sceptical of authority. They're often screw-ups. And through it all, they trudge on, balling up their schoolboy fists and putting down their heads despite tremendous odds.

"I'll be glad to be rid of you, Flint," one colleague observes to Miles, although it's a remark that could just as easily be made to Rebus. You sound like a conscience, but your eyes are full of tricks."

Both can be foes to their friends and comrades to their enemies, a blurring of loyalties that elevate them to the upper ranks of fictional detectives worth caring about.