The second in his Accursed Kings series, The Strangled Queen takes up the story of Louis X of France and his adulteress wife, Marguerite of Burgundy. Although the title pretty much leaves little to the imagination as to what happens to poor Marguerite, the majority of the book focuses on the political struggle between the king, his nobles, his brothers and his uncles (especially Charles of Valois).
Druon is a really good writer but he has a nasty habit of yanking you of the story for some philosophical statements, and telling the reader of future events. At one point as he describes the harshness of medieval life and it seemed so melodramatic that I could hear it in my mind in that voice from the Ten Commandments (the one that narrates from time to time - here is a link to that section of the movie: http://www.youtube.com/watch?v=yrbSx3oiBHk to give you an idea of what I was hearing!).
Unfortunately, English translations of Druon's work can be hard to find and expensive.