In fifteenth-century Constantinople, Prince Constantine saves the life of a broken-hearted girl. But the price of his valour is high. John Grant is a young man on the edge of the world. His unique abilities carry him from his home in Scotland to the heart of the Byzantine Empire in search of a girl and the chance to fulfil a death-bed promise. Lena has remained hidden from the men who have been searching for her for many years. When she`s hunted down, at last she knows what she must do. With an army amassing beyond the city`s ancient walls, the fates of these three will intertwine. As the Siege of Constantinople reaches its climax, each must make a choice between head and heart, duty and destiny.