Wales, Ireland, Scotland and Cornwall. Great places to go on holiday and relax in the summer - in daylight. In the long nights of winter it's a different story. Bleak moors; bare, frozen mountains, rough seas. And that's just the natural world. What about the ancient stone circles, ruined churches and dark castles which litter the landscape of the Celtic lands? It's not surprising that many of the greatest ghost stories ever written came out of this background.