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.