Ian Rankin dedicates his seventeenth John Rebus novel "to everyone who was in Edinburgh on 2 July 2003". The first half of the book is a pacy, punchy read, set against the backdrop of the G8 summit held in Scotland that year. In the first chapter, Mickey, Rebus's wayward younger brother whom regular readers will remember from the earliest books in the series, is barely in his coffin when John's close colleague Siobhan Clarke calls to let him know that there is a break in a six-week-old murder case.

The victim, Cyril Colliar, was an unpleasant criminal who worked for Rebus's nemesis, "Big Ger" Cafferty. Although the police aren't exactly busting a gut to find Colliar's killer, Cafferty wants vengeance, if only to demonstrate his clout in the dog-eats-dog criminal fraternity. Clarke's breakthrough discovery of clothes from three victims at a remote spot called Clootie Well leads her and Rebus to realise that a serial killer may be at work - what is more, a killer who targets sex offenders, possibly via a website called Beastwatch.

While Rebus and Clarke are trying to find a link between the victims, another tragedy occurs: an idealistic young MP falls from the walls of Edinburgh Castle during a pre-G8 dinner. The detectives are blocked from investigating the apparent suicide by Special Branch, who claim jurisdiction. Rebus is suspicious, not least because of the involvement of party donor and arms dealer Richard Pennen, and refuses to let go of the case.

Having set the scene, the book describes the day of the anti-war procession before the G8 summit. We see the events from all perspectives: that of Clarke's parents, who turn out to be idealistic teachers who have travelled to Scotland to camp out and join the demo, the police and security forces, the disaffected young residents and the unsympathetic local councillor, Trent, who seems to crop up everywhere. Events are portrayed vividly as Rebus is, as usual, irritated by and in turn irritating anyone in authority, and as Clarke becomes increasingly concerned about her parents', and even her own, safety, as crowds threaten to turn into mobs.

The description of "the naming of the dead": a thousand victims of the Iraq war, is movingly described, as is Clarke's realisation that this also describes her calling:

"She named the dead. She recorded their last details, and tried to find out who they'd been, why they'd died. She gave a voice to the forgotten and the missing. A world filled with victims, waiting for her and other detectives like her. Detectives like Rebus, too, who gnawed away at every case, or let it gnaw at them. Never letting go, because that would have been the final insult to those names."

The book loses momentum after the day of protest is over. Rebus and Clarke seem to spend much of the next few days in a holding pattern while the author is diverted into describing the arrival of the G8 leaders, making political points and observations, and impressing us with his musical knowledge, instead of pressing on with the plot - although the sudden shock of the London tube and bus bombings of that year is well-told, dovetailing cleverly with events in Scotland.

The investigation is not short of incident: Rebus is kidnapped for an uncomfortable night in the cells; an escort girl (Molly) and a protestor (Santal) turn out to be more than they at first seem; there is definitely something dodgy about Trent and his association with the young mob element; and confusions abound as Rebus and Clarke pursue different ends of the investigation while unable to communicate effectively owing to the road blocks and other security measures. Inevitably, as this is a Rebus novel, the detectives are suspended from duty for failing to prioritise the security agenda over their pursuit of the criminal(s), but again inevitably, they press on regardless and although this infuriates the Chief Constable, nobody in the police force seems to care what Rebus is up to or tries to stop him from continuing to work from his flat. A year away from retirement, and a known maverick, Rebus's superiors seem content to bide their time until time itself takes away the man who doesn't fit the new order of policing.

Journalist Mairie Henderson makes a welcome reappearance in this book; with her help as well as that of Clarke's erstwhile suitor Eric, the two police detectives (mainly Rebus, it has to be said) solve most of the various mysteries that grow up during the course of the narrative. By the end, Rebus has the satisfaction of striking a blow against political corruption and his tormentors, as well as seeing Clarke saved from his own fate of being in the power of the nasty but unconvincingly portrayed Cafferty.

Even though the entangled crimes are all tied together in quite a neat resolution, I'd lost some of my interest because of the book's meanderings. Further, the motivation of the person eventually found to be responsible for the Clootie Well killings does not ring true. The Rebus series remains a must-read, but this particular outing would have benefited from more focus on the key characters (Rebus and Clarke, mainly, but others are too sketchy or undeveloped) and details of the investigation, and less on the injustices of globalisation and foibles of politicians or their hangers-on.