Where did you get the idea for your most recent book?
I tend to base my books on facts - i.e. I graft fiction on to fact. In practice I will come across some little known medical or scientific fact and imagine the worst possible scenario arising from this and write the book.
With THE SECRET I was puzzled as to why Polio was still endemic in certain areas of the world when strenuous efforts had been made to eradicate it. I discovered that the vaccination schedule in one of the worst areas - the border region between Afghanistan and Pakistan - had been damaged by the insertion of fake vaccination teams put in by the CIA to gather intelligence.