Dear Reader, while of course I’ve read Arthur Conan Doyle, he didn’t technically classify as what we know as Golden Age, so, despite me taking a Holmesian approach to my own investigation, I didn’t write about him. I explained this to Juliette.

‘I’m more interested in people like Ronald Knox. He was part of the establishment of crime writers in the thirties. Anyway, I don’t write novels, I write how-to guides. You know: Ten easy steps to your first mystery; How to be an Amazon bestseller. That kind of thing.’

‘Oh, I get it. You write books about how to write books that you’ve never written, bought by people who will never write one.’

Honestly, she had it spot on. You’d be surprised how many unfulfilled novelists are willing to shell out a buck ninety-nine for the feeling of progress. My books aren’t bad, but my business isn’t really helping writers, it’s wish fulfillment. I’m not proud of it, but neither am I ashamed.

‘It’s a living.’

‘Who’s Knox then?’ she asked.

‘He wrote a set of rules for detective fiction in 1929. In my books I compare them against modern-day murder mysteries. Pretty much all of them are disregarded, shattered into pieces, by current fiction, which tends to like to cheat. He called them his ten commandments. Conan Doyle pre-dates him. Why is he a crackpot?’

‘He believed in fairies, for Christ’s sake. Tried to hunt them down. After the death of his first wife and son, he tried to speak to them by séance. He thought his nanny was a medium. The man was so mad, he tried to convince Houdini, who openly admitted that magic wasn’t real, that Houdini himself was magic.’

‘That’s one of the commandments,’ I said, pausing to wonder whether a man who died in a fire and didn’t melt any snow qualified as other-worldly. ‘Number 2, in fact. Nothing supernatural.’

‘So these rules – that’s why you think your brother asked for you and only you? That’s a long bow.’

‘No. I think he asked for me because I’m the least Cunningham of the Cunninghams.’

‘What’s that mean?’

‘I’m not one of our lot.’ I meant it to be playful – didn’t I? – but it came out laced with acid. I’d missed the mark.

‘I didn’t mean—’ Her thought fizzled halfway through. She shook her head, closed the computer window and stood up. ‘Actually, you’re right. I should share this with Crawford instead. And let’s hope to God there isn’t a real murderer out there, or our lives are in the hands of an author. I suppose we can beat them to death with one of your hardbacks.’

‘Digital only.’ It came out as a squeak. ‘I self-publish.’