each knows the other for a rival, an ally, a pawn, destined - with Margaret's younger sister Mary - to a sisterhood unique in all the world. The three sisters will become the queens of England, Scotland and France. United by family loyalties and affections, the three queens find themselves set against each other. As they experience betrayals, dangers, loss and passion, the three sisters find that the only constant in their perilous lives is their special bond, more powerful than any man, even a king.