Few cities have been stripped quite as bare by fiction as Ian Rankin's Edinburgh. With 11 novels completed in just over a decade, Scotland's top-selling author has created a place that is unrecognisable to the casual visitor or tourist, a place much closer to Hugh MacDiarmid's "mad god's dream/Fitful and dark" than to the centre of arts and culture dreamt of by outsiders. Rankin's Edinburgh is a divided city - divided between old and new, and between Hibs and Hearts; it's a city defined by the past more than by the present, and only with the prospect of a new parliament does it give its first nervous glance towards the future. Above all, it's a hidden city: reserved, self-contained and filled by people who keep their emotions and secrets concealed - a city where you could live for years without glimpsing what is below the surface. The quest to understand this strangest of places, to get to what he calls its "dark, shrivelled heart", is what drives both Rankin and his creation, Inspector John Rebus, and each pursues it with a zeal worthy of the Holy Grail. Edinburgh is more than a backdrop to these astonishing novels; it is the reason for their existence.
Set in Darkness is Rankin's best novel to date. In it, he effortlessly weaves together multi-layered storylines to reach a conclusion that manages to be both unexpected and inevitable. Assigned to one of many subcommittees advising on security issues for the first Scottish Parliament in 300 years, Rebus is thrown into a series of cases that are typically complex and superficially unrelated: the discovery of a long-dead corpse in Queensbury House, home to Scotland's new rulers; the high-profile murder of a prospective Labour MSP; the suicide of a tramp with over £400,000 in his building society account; and the escalating violence of a serial rapist who targets women in singles clubs. As if that weren't enough, he is forced to work alongside his very antithesis in policing - a paper-pushing boy on the fast track to chief constable - and must face the unexpected prison release of Edinburgh's most notorious criminal, a man who, through the kind of twisted relationship that only mutual hatred can foster, has become closer to him than his own family. Even by Rebus's standards, this is a bad week.
Taken from a 19th-century poem by Sarah Williams, the title could easily act as an umbrella term for the whole series. Rankin's fiction has always relied on an interplay between the shiny surface and the darkness below. Here the history, museums and royalty provide a gloss to the criminal underworld, and the glass surface of modern architecture masks a new parliament that is tainted before it starts; even the prisons are not immune to the charade of image and reality, revamping their visiting areas with new chairs and a play area for children, while behind the scenes slopping out remains a fact of life. Set in Darkness, however, develops an aspect of Rankin's writing that has been much less evident in its predecessors: a readiness to combine this bleakness with extraordinary compassion. The unrelenting energy of James Ellroy, the starkness of Irvine Welsh - both find echoes in Rankin's particular brand of noir, but they are tempered by enormous sympathy and understanding. Rebus may be a loner who spends more time in his head than in the company of others, he may live perpetually surrounded by loss and haunted by ghosts of the past, but there is more room in his life these days for the underdog: for the dead tramp's girlfriend, dressed in scraps of black clothing and a different style of shoe on each foot; for the people trying to hang on to a city that is changing in ways they don't understand. His motivation to get up in the morning is not a love of law and order, or a desire to avenge the victim; it is atonement for some kind of collective, indefinable guilt that no amount of whisky can dispel.
Few aspects of contemporary Scotland have escaped Rankin's attention, yet he is neither an issue-based writer nor a crusader; with sparse, clear prose and a refusal to overdramatise, he describes social realities from homelessness to political corruption in a way that highlights convincingly - and movingly - the levels of despair to be found in each. In Rebus's world, the crime is the least important of the problems to be solved; invariably, it is the only one that ever finds an answer. That refusal to simplify, to restore order at all costs, makes Rankin a writer who has shown just how far the boundaries of crime fiction can be stretched.