Katherine comes to the court of Edward III at the age of fifteen and is dazzled by the feasts, jousts and entertainments of the wealthy nobles. She is naive, convent-educated and the orphan of a penniless knight, nevertheless she is beautiful and she turns the head of a number of young men including the King's favourite son John of Gaunt. But he is married, and she is soon to be betrothed. A few years later their paths cross again and this time their passion for each other cannot be denied or suppressed. Katherine becomes the prince's mistress, and discovers an extraordinary world of power, pleasure and passion.