It is a hot summer’s day in the tourist village of Avebury.A man sits outside the Red Lion pub, waiting. He sees a woman with three young children, two of them running ahead while their sister dawdles behind. A child’s voice catches on the breeze.

For want of anything more interesting to do, the man watches. He sees nothing sinister or threatening. Even when another figure enters his field of vision, he does not react. The figure is ordinary - male, short-haired, stockily built.But he is moving fast, at a loping run.

And then it happens. In one swift movement, the running man grabs the youngest child and carries her away. Still the man outside the pub does not react. Suddenly, awhite transit van bursts into view, its engine racing, its rear door slamming shut.The child and her abductor are inside. The child’s sister rushes forward. The man outside the pub jumps up…

The tragedy begins at Avebury. But it does not end there.

It’ll be clear to many of you by now that I shamelessly exploit the writing of my novels to pursue historical enigmas that have bounced around in my head ever since I got hooked by the whole business of history as a child. (That there never was going to be any other subject I studied at university was something I realized long before I was sure of going to university at all.) Sight Unseen is a classic example of that, the enigma in this case being the late, great and never conclusively identified eighteenth century writer of politically explosive letters to the press under the famous (or infamous) pseudonym of Junius.

Present day politicians get off very lightly compared with their eighteenth century predecessors in terms of the savagery with which they are lampooned by cartoonists and satirists. But Junius went beyond satire. He was a  barb to governmental flesh during the three short but busy years of his letter-writing campaign (1769-1772) because he was possessed of a large amount of very embarrassing inside information about ministers and their friends and wives and mistresses. He was, in short, one of them. But which one? Who was he? No-one ever found out. Like Jack the Ripper, Junius acquired immortality by quitting while he was ahead. And, despite historians’ best efforts, he’s stayed ahead ever since.

What’s Junius to do with the abduction of a child at Avebury, the prehistoric stone circle in Wiltshire, one summer afternoon in 1981? On the face of it, surely, nothing. But a way of connecting the Junius mystery to a modern unsolved crime came to me with astonishing clarity as I walked around an eerily deserted Avebury one winter morning in 2004. The plot that started to form in my mind that day has several layers of surprise built into it, all represented by the multiple meanings of the title. Sight Unseen. We accept things without properly examining or questioning them.  Maybe what we think we saw we didn’t actually see. And maybe by examining and questioning we can come to understand an event anew – to unsee it, as itwere. That is what the central character in the story, historian and Junius expert David Umber, has to do. And that’s what this book invites you to do, along with him. Enjoy the ride.