In Tudor England, traitors are everywhere and the queen's spymaster, Sir Francis Walsingham, is assembling the greatest intelligence-gathering network in the world. Walsingham's only daughter, Lady Frances Sidney, is smart, courageous, and unhappy in love. She longs for the excitement of decoding encrypted messages and setting traps for those working for rival Mary, Queen of Scots. But Frances's father refuses her any opportunity to contribute to the desperate effort of keeping England safe.
Then Elizabeth, impressed with Frances's fiery spirit, calls her to court as a lady-in-waiting, and Frances seizes the chance to prove herself. Soon, she wins the trust of her father's de-coders and begins her secret work, thrilled with the freedom to test her talents. But her peril is compounded as her beauty and wit also attract the romantic attention of two men, one the reckless Earl of Essex and the other her own brilliant but low-born servant, Robert Pauley. And when Frances uncovers the most dire plot of all, she will risk her father's condemnation, her heart's longing, and her very life to safeguard her queen.