Brown has taken the action to a whole new level. There's enough violence and gore in this installment to guarantee that Tom Hanks will be putting on his jacket for a third movie adaptation. And it drew me in hook, line and sinker. There were moments when I was literally holding my breath and speeding through the pages to find out what was going to happen next.

And then? nothing. I laughed out loud at the great 'twist', because I'd seen it coming from miles away. The novel's secret is not only unsurprising but not half as shocking as my inner conspiracy theorist would have wanted. I was frustrated, and I felt betrayed by Brown's writing.

Guilty pleasure

At times he's equally inept at handling the book's Big Themes of faith and the connection between man and God. He seems out of his depth as, in the space of a few chapters, he tries to delve into questions that have been the source of much debate over the last centuries. It brings a deeply serious tone to the novel that doesn't fit with the sense of fun, and begins to feel more like a cross between a sermon and a self-help book.

But 'The Lost Symbol' is fun. It's addictive, and as a colleague says, entirely disposable. It's a read-once, read-quickly, and by no means a literary work of genius, but so long as you don't try to take it too seriously, it's a gem of a 'guilty-pleasure' novel. And his publishers will be grinning smugly to themselves as they watch their bank balances soar.