Young Katherine Gray, the younger sister of Jane, Queen of England, known in history as the “Nine Day Queen,” expects only good things from life: she is rich, incredibly beautiful and passionately in love with her fiancé, who is also looking forward to their wedding day. But soon the girl realizes that the Tudor blood that flows in her veins is a real curse. She accidentally discovers the diary of Catherine Plantagenet, the illegitimate daughter of the notorious Richard III, and learns that her namesake, who lived a century before her, was desperately trying to unravel one of the most terrible mysteries of the Tower of London. Then Katherine Gray undertakes her own investigation, not even imagining that she, too, will soon find herself behind the impenetrable walls of this gloomy dungeon...