I haven't read a word of it.
I got about 4 sentences about the book's plot out of her. I said 'and let's see. There's this and there's that and there's this and there's that and there's this?'
'...yeah...' she said, blinking at me.
'That's Holy Blood, Holy Grail with a liberal smattering of Umberto Eco's Foucault's Pendulum. Not Mr. Brown's plot- Eco's and the Prieur de Sion's.'
'Why would the Prieur de Sion have spread all this information about themselves?'
'No no. Himself. Sion is a fictional chunk of the world, and a prieur is a prior-- that is, the religious gentleman who resides in a priory.'
'Yes. It's not an organization. It's an office. A role. A person. Allegedly, a person in this office found some gold which may or may not have been buried Templar treasure.'
'Where'd that come from?'
'Oh, uhm... there's a website, you can find it by doing searches on Holy Blood Holy Grail.'
When a book's BRILLIANT SCHEME AND CLEVER PLOT can apparently be summarized by bouncing around bits of my pleasure reading from 10 years ago, I find that its scope seems to move from 'grand literature'.
If you like The DaVinci Code, I'd especially recommend Holy Blood, Holy Grail.
If you're curious what people with knowledge of the fields that Mr. Brown dabbles in have to say, I recommend this article at the Chicago Tribune, pointed out to me by welcomerain.