'I AM the Myra Hindley story," said Jimmy Savile.

The line stopped me in my tracks. I turned to old notes I'd taken, jottings in the margins of books on the Moors Murders, and yellowed files I'd kept over the past 20 or more years as a crime reporter. I could find nothing connecting Savile to Ian Brady and Myra Hindley. Here though, in a throwaway line, in Dan Davies's investigation into the life and lies of the DJ, was a hint that Savile - perhaps the most prolific sexual predator and paedophile in British history - was in some way intimate with the Moors Murderers.

Savile's modus operandi was to raise spectres with those in his circle, and then let the spectre disappear like the wreath of cigar smoke that hung around his bleach-blond head. There was no such thing as a straight answer from Savile, and so there is no unravelling of what Savile really meant when he said "I am the Myra Hindley story". That's all he gave. So, we struggle - as with everything we try to pin down and learn about Savile - to piece together the truth. All we can do is take this shred of evidence and connect it to another, such as the claims of Janie Jones, the madam and former pop star immortalised by The Clash, that when she was released from Holloway Women's Prison in 1977 after serving three years for controlling prostitution, she received a summons from Savile. The flamboyant Jones had befriended Hindley in prison. Savile had been the DJ at a Manchester dancehall frequented by Brady and Hindley, he claimed. He bragged to Jones that he knew Brady. "He said it was disgraceful that I was siding with Hindley," says Jones.

When it comes to Savile and the Moors Murderers, these are all the pieces we have: a dancehall meeting, a few quotes from an icon of the sexual demi-monde, and Savile's own strange, gnomic comment.

Savile passes through British social history like a criminal Zelig. His life takes us from the two-up-two-down 1920s depression slums and the Brighton Rock spiverry of the late 1930s, to the mines of the war-era Bevin Boys, the rise of rock and roll, The Beatles, pirate radio, the birth of the charts, the creation of celebrity culture, Saturday afternoon TV, the Thatcher years, the royal family, the NHS. This was his world. He was friends with the stars - mates with Elvis and John Lennon - a confidante of Thatcher and court jester to the royals. A number of major hospitals - particularly Broadmoor and Stoke Mandeville - were his private fiefdoms, and the BBC was his pay packet and passport to fame - fame which he used to rape and abuse children and vulnerable adults wherever he could find them, whether it was in a wheelchair in a hospital ward or a dressing room at Television Centre. The Moors Murderers are just one of these many totems of the 20th century, which he brushes against and then moves past, as was the Yorkshire Ripper.

Savile was once summoned by West Yorkshire Police to provide a cast of his teeth by the Ripper Squad. Bite marks had been found on a number of the Ripper's victims, and the third woman to die, Irene Richardson, was dumped near a flat Savile had just moved into. A number of members of the public had anonymously pointed to Savile as the serial killer. A friend of the doctor who took the cast of Savile's teeth maintains the DJ was a suspect because he was known to use prositutes in the Ripper's hunting grounds in Leeds. Savile later went on to befriend Peter Sutcliffe after he had been convicted of murdering 13 women and was confined to the high-security state psychiatric hospital Broadmoor.

Savile spread corruption wherever he travelled, gangrenous through society. Police officers were sucked into his orbit and became his friends and defenders. Politicians lauded him: Thatcher seemed obsessed with getting him a knighthood, and Edwina Currie wrote in her diary "Attaboy!" of Savile at the same time as he was making intimidatory efforts to stop a strike at Broadmoor which she oversaw as a health minister. The royals adored him. And this, to a man who liked to call himself The Godfather, was guaranteed protection.

This book isn't just about Savile, though, it is about what some people have now come to term "different times", as if in the 1950s, 1960s and 1970s paedophilia was somehow abnegated because rock and roll was cool and shaping the permissive society. Savile would roll into towns and villages throughout the land for charity functions and discos, and tell local councillors and newspaper reporters that he expected "dolly birds" and "virgins" to be laid on to meet him. He got what he wanted. Sometimes the girls were encouraged to spend the night camping with him. He made joke after joke after joke about schoolgirls and underage sex. Perhaps, in an era when The Rolling Stones could sing about the molestation of a runaway - in the song Stray Cat Blues, which contains the lyrics "It's no hanging matter / it's no capital crime / I can see that you're 15 years old / No, I don't want your ID / and I can see you're so far from home" - Savile's attitude seemed simply a more coarse and vulgar way of expressing a lackadaisical, amoral confusion about the revolution in sexuality taking place across the western world. The confusion, though, was perfect camouflage for predators like Savile, because it also created a dangerous world, blind to the young and vulnerable.

David Peace, who wrote the Red Riding Quartet, set against a backdrop of police corruption and the Ripper murders, has compared Davies's book to two giants of new journalism, The Executioner's Song by Norman Mailer, exploring the case of Gary Gilmore, and Happy Like Murderers by Gordon Burn, which unpicked the lives of Fred and Rose West. The book is not as good as those two masterpieces. Mailer and Burn elevated journalism to art. But that is not to condemn Davies. His work is an excellent piece of investigative journalism. While he cannot fully pull back the mask on Savile - he is too elusive to grasp and examine - he does a wonderfully disturbing job of unveiling the world in which our parents and grandparents lived.

The book had a curious effect on me. Few books give me nightmares. This did. But it also changed my thinking about the nature of many of the criminals I have come across in my working life. I've met a lot of rapists and paedophiles. I usually meet them in prison, after conviction, when they are broken and craven, protesting how sorry they are, claiming they've been set up, or outright denying their guilt regardless of the welter of evidence against them. Obsequious hand wringers. Uriah Heeps on segregation.

For years, detectives I know described these sex offenders as staggeringly boring men. They might come from every background, class, race and religion, but they were unified in one characteristic: their overwhelming lack of charisma, their crushing ordinariness - people no-one would notice at a party, let alone invite to a party. The banality of evil has become a banality itself, but it is a safe box in which to put such men. Or so it seemed.

Increasingly, though, my detective friends appear to have got it wrong. Jimmy Savile, Stuart Hall, Rolf Harris, Gary Glitter - these weren't nobodies. They were oddities demanding and getting attention; the larger-than-life eccentrics from our collective childhood, from the long hot summer that was the 1970s. These were our clowns. They spoke funny, they dressed funny, they acted funny, and to many, these jesters were very funny indeed. They made Britain laugh with their weirdness and otherness. The clothes, the patter, the hair, the attitude. They weren't the slithering sex offender hiding under a rock, they were as the title of the book says, hiding "in plain sight". They offended while we watched, made us complicit in their crimes. Celebrity entails followers. The British people followed these showmen, and in our rush to tag along behind fame and glamour, we gave them permission to offend - and that is the ugliest revelation of all in this grim and gruelling but necessary book.

Neil Mackay is the Sunday Herald's Head of News and author of the novel All The Little Guns Went Bang, Bang, Bang