On a Leicestershire battlefield in 1485, the course of British history changed. One man, a minor Welsh noble, was instrumental in effecting this change, enabling the establishment of the new Tudor dynasty. This little-known historical figure was Rhys ap Thomas, who claimed descent from Urien Rheged, one of the knights of King Arthur. Born in Carmarthenshire in West Wales, he had spent his early years in Burgundy with his father, in exile, as had two other men, Henry Tudor and Richard III. The three young boys were to meet many years later on the battlefield, where the lives of all three would change forever. This is the story, set in the turbulent period of the Wars of Roses, of Rhys ap Thomas, whose claim to fame would be 'the man who killed Richard III'.