Aquitaine, an English possession, is in crisis. It is under threat from neighbouring nations and internal dissension.
The Black Prince, King Edward III’s eldest son has been given the task of taking command in Aquitaine.
Suddenly there is an opportunity. Ximene Trencavel is the heiress to the lands of Occitan, to the east of Aquitaine: lands controlled by the Franks.
Ximene wants independence, both for herself and for Occitan. A union between Aquitaine and Occitan would be mutually beneficial.
The Black Prince undertakes a secret journey to meet Ximene to negotiate a marriage contract. It is, however, a marriage neither of them really wants.
Meanwhile, the Franks plot to murder Ximene to prevent ,not just the marriage, but any kind of union between England and Occitan.