I've been asked this week whether I'm a Gnostic. This hasn't surprised me, given the contents of my latest book, The Keystone, which is just entering its third week of public life and getting into the hands of more and more readers. There are Gnostics afoot there, my friends -- good Gnostics, bad Gnostics, old Gnostics and new.

'And what about you, Mr Dean?'

I don't mind the question, though I do find it mildly amusing.

The book is also filled with murderers, though no one's yet enquired as to whether I am, apart from being an author, also secretly a vicious killer.

And while it also features capable FBI agents and leaders, I've yet to receive the call asking whether I had to put my career with the Bureau on hold in order to write the book.

'But are you a Gnostic, Mr Dean?'

It is strange what gets assumed of authors when we read their books -- and I say 'we' here because I am just as guilty of this as anyone else. I've just finished a rather good book from a few years ago by Scott G. Mariani (The Heretic's Treasure), and have to admit there were moments when I wondered just how much time off he'd had to take from curating Egyptian archaeological exhibits to craft that pleasant read; and yet I wasn't wondering whether he was also an arms dealer, despite his clearly expert knowledge of guns.

I am waiting for those other questions to roll in. For readers to write, having read through The Keystone, to ask, 'Are you really an octogenarian staffer of the British Museum?' 'What are your real connections with Iraqi terrorism?' 'Do you build a lot of bombs in your spare time, then?' 'What have you got against Chicago?' 'Do you take your notebook with you when you repel Egyptian cliffs, or just remember the details when you get home?'

But I rather assume what I'm going to continue to be asked is the same question I've heard before.

'Just tell us, then: are you a Gnostic?'