During the sixteenth century Sir John Dexter, an English Catholic exile, makes a new life as a soldier of the king of Spain in the war against the Ottoman Turks around the Mediterranean Sea. Five hundred years later, Tom Dexter, a descendant of Sir John, is a member of Britain's Secret Intelligence Service (MI6) carrying on the war against terrorism in which he opposes the modern day forces of militant Islam. The two men inhabit very different worlds, centuries apart, yet there are linkages between their experiences. The novel interweaves the two worlds and different destinies of Sir John and Tom. It follows Sir John through his experiences in the great events of his time, including the siege of Malta and the great naval battle of Lepanto. In the modern world Tom and his American colleagues in the CIA are on the trail of Islamist terrorists and their deadly missiles, but Tom is dangerously distracted by his love for Susie Marsden, who has her own agenda. For Tom, as for his ancestor Sir John, the climax of his endeavours takes place in Morocco. That country becomes the crossroads of the years.