She yanked the padlock free, the chain coming with it. Pulled open the gate.

And was picked up off the ground by Rebus, his hug enveloping her.

‘Ow, ow, ow,’ she said, causing him to ease off. ‘Bit bruised,’ she explained, her eyes meeting his. He couldn’t help himself, planted his lips on hers. The kiss lingered, his eyes shut, hers wide open. She broke away, took a step back, tried to catch her breath.

‘Not that I’m not overwhelmed or anything, but what’s this all about?’

— Ian Rankin, A Question of Blood

"What’s all this about?" Ah ha, that’s asking. That long, slobbery smooch was just a snog waiting to happen as every reader knew from the sexual chemistry seething on every page though the guy and the gal never even let it into their thoughts. No, they sublimated it. He wants to protect her, she tries to mother him though he is much older than her — and there lies the rub. Theirs is a mutual attraction that dares not give itself away because of the generation gap: who wants to be a sugar daddy, or a Lolita, especially on the police force? As it is, they happen to be partners.

And that’s how Detective Inspector John Rebus and Detective Sergeant Siobhan Clarke play it — partners, friends, but not lovers — until almost the very end of this thriller when Rebus rushes to Siobhan’s rescue. He finds her alive and is so relieved he forgets himself — and plants that long, wet kiss. And, breathless, she asks "what’s this all about?" as if she doesn’t know — and she a detective! Is she being naive or coy?

The author, Ian Rankin, doesn’t explain. He cuts away to the last chapter where Siobhan is in hospital, recovering from a slight injury, with Rebus at her bedside. But we know they can no longer pretend to be just partners in the cop shop.

They certainly make an attractive pair. Rebus is a modern Philip Marlowe. Siobhan is feisty and caring, smart and devoted. It is their relationship which finesses the Rebus stories. Mystery is not the right word for Rankin’s novels. He may be Britain’s most successful crime fiction writer today but he can’t be compared with Christie or Conan Doyle because he doesn’t write typical whodunits. One reads him as much for his description of people and places as for who killed whom and why.

Going through A Question of Blood, I realised I had read it before. But that didn’t stop me from carrying on. Unlike the typical whodunit, where you want to get to the bottom of the mystery, here I wanted to linger among the people and the places and the music that accompanies Rebus and Siobhan wherever they go. A police procedural as full of character as a traditional novel and also a literary jukebox — that’s how I would describe this book.