Book excerpt: Reay Tannahill's great bestseller is the story of one extraordinary woman's determination to win back her birthright - the remote and beautiful West Highland castle of Kinveil - sold by her father to a Glasgow merchant when she was seven years old. It is also the intricate picture of a family in the heyday of the British Empire, an epic story spanning almost a hundred years and stretching from Edinburgh to the Crimea, from an expanding America to the India of the Raj.