There's a man following me.
I know this sounds paranoid, but he's definitely there: in fact he's everywhere. It started earlier this year when my book Sanctus was published. I was warned it would happen but, like a fool, I didn't pay any attention: I should have listened to my agent.
"They love it", she said, when the first publisher nibbled at the manuscript.
"Great." I replied.
"They said it reminded them of The Da Vinci Code."
"Brilliant."
"They said they couldn't put it down - just like The Da Vinci Code. That's great, isn't it?"
(Cryptic pause) "Maybe, we'll see."
Fast forward a year and Sanctus has now been published in over 50 countries and translated into 27 languages. For this I am both humbled and deliriously happy. I'm like a dog with three tails - but my agent was right. In every single one of these countries almost every review I get mentions Dan Brown in some form or another, and it doesn't seem to do me much good either way.
Those who REALLY love Dan Brown are like an elite but shadowy force apparently united in their mission to hunt down any other writer who dares tread on the hallowed ground of religious conspiracy. For these people any book that isn't the book is considered heresy.
Then there are the apostates - the ones who didn't actually like The Da Vinci Code and think that its incredible popularity and success has somehow diluted the one true faith of literature. To these people my book is merely more evidence of the spread of this foul poison.
So I'm damned either way.
When I set out to write Sanctus all I wanted to do was craft a piece of high quality entertainment. I wanted you to read the first page and be intrigued enough to read the next until you found yourself in the middle of the night on a school day cursing my name like an addict cursing his pusher.
So I picked the best idea I had at the time and wrote like my life depended on it - which it did in some ways because I'd quit my job to give myself the time to do it. It just so happened that my best idea featured the church and the secrets they keep. I'm pretty sure if my best idea had involved lawyers then maybe I'd have John Grisham on my tail now.
And I'm certainly not the first author to tiptoe into the conspiratorial, religious tinged territory, but - and I hate to break this to the faithful - neither is Dan Brown. Umberto Eco's The Name of the Rose is, thematically at least, much closer to Sanctus and came out 23 years before Dan Brown decided to become a particular type of God botherer.
For me, what binds my book to Eco's and Brown's is not their shared religious themes, but the universal story of an individual challenging a formidable institution and winning. We have long suspected that the faceless organisations that run our world - be it the church, multinational conglomerates or the government - keep things from us.
They watch over us and control the information and, by doing so, they also control us. But in the modern age, where information has been democratised by the internet and the spread of social media we no longer suspect this is the case - we know it to be true.
You just have to look at recent headlines to see evidence of this: Wikileaks, the phone hacking scandal that has engulfed NewsCorp, the Catholic Church apologising for the systematic protection and cover up of decades of Paedophile priests in Ireland. In all of these cases it's the truth that matters, and we arrive at it only by questioning. And this, I think, is why we are all slightly obsessed with conspiracies at the moment; they ask big questions and challenge what is presented as the truth; some of the theories may well turn out to be right.
So if you do come across Sanctus in a bookshop, please see past the cross on the cover and the sinister outline of a monk and just read the first page and make your own mind up. If it's still not for you, then that's fine, just put it back and walk away.
Just make sure you're not being followed. I've heard that Dan Brown has agents everywhere...
Sanctus can be bought from Simon's Amazon page.