It's another moment of suspense in the career of the fictional detective Inspector John Rebus. How will audiences at the Edinburgh International Book Festival respond to a crime novel from the writer Ian Rankin which does not feature his most famous literary creation?

Rankin has told the Times that he hopes to be able to use the festival in August as a launchpad for an Edinburgh-set comedy thriller, which is to be formally published the following month.

The novel is his first work of crime fiction since he completed the 17th and apparently final instalment of his best-selling Rebus series, which followed the career of the curmudgeonly detective and his put-upon sidekick, Siobhan Clarke.

Lighter in tone than its predecessors, this latest novel is an expanded version of Doors Open, a serial that appeared last year in the New York Times. “I've beefed it up because my publishers liked it. That was great because the characters were little more than thumb-nail sketches in the serial and I've been able to flesh them out,” said Rankin, who has nearly trebled the size of the original work.

“Rebus gets a very tiny mention in the book, but only because the cops are glad to see the back of him.”

The light tone is a departure for a writer seen as one of the founders of the “tartan noir” school of crime fiction. His best known detective series was written in real-time, and concluded last summer with the publication of Exit Music, when his fictional hero reached the retirement age of 60.

Rankin, who has since written the libretto for a work performed by Scottish Opera and penned the lyrics for a song by the rock band St Jude's Infirmary, did not rule out a return to more familiar territory. “Come autumn, I might think, ‘Do I want to write about him again? Or do I want to write about Siobhan. If I write about Siobhan, will he be a part of it. At the moment, I'm still undecided,” he said.

Rankin has attended Edinburgh's book festival every year since it was founded in 1983, but in 2007 he achieved more prominence than usual after he became embroiled in a literary spat with his fellow crime novelist, Val McDermid.

Under the newspaper headline “The revenge of the bloodthirsty lesbians”, he speculated on what he claimed was the propensity of lesbian authors to linger over their goriest scenes, an observation dismissed by Ms McDermid, who is lesbian, as “arrant rubbish”.

Rankin said that reaction to the story had been overblown, and he remained on friendly terms with her.

“I've bumped into her at least once. There has been no revenge, at least, not that I know of,” he said. At this year's festival, Rankin will host the opening event, an interview with a leading but as-yet unnamed politician. He said he was keen to attend a number of other events, particularly those featuring Rick Wakeman, the former Yes keyboard player, and a discussion with Alex James, formerly of the band, Blur.

“This is an important festival if you are interested in culture, politics or the environment. I've been at every festival, and I've scrutinised every programme since the start. I thought I'd be jaded this year. But when I got the programme, my God, ‘I thought I want to see him, I want to see her.'

“I want to go and see Rick Wakeman so much, I put my name forward to chair it. But they wouldn't let me.”

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