Robert Cecil, Secretary of State to James I, has a problem. He owes a vast and secret debt to the Prince of La Spada, who is dying and has called in the loan – and Cecil cannot pay. Even worse, he has staked as security, without royal authority, the King's Great Pearl. To Cecil's surprise, the Prince will agree to a hostage but he wants Cecil's firemaster: Francis Quoynt, the best in his dangerous business. Cecil immediately seizes the chance, for Quoynt also serves as his spy.
La Spada is a wealthy, beautiful Italian city–state – the gateway of Europe. Whoever controls the mountain passes of La Spada also controls the flow of intelligence and much of the trade from the Middle East. As his mind disintegrates into fantastic obsessions, the Prince makes his treacherous illegitimate son his heir. Which thwarts the deadly ambition of his daughter, Sofia – the Principessa.
Sofia is young, seductive, wily and recently widowed. Already a blooded player of politics, she could outdo Lucretia Borgia in the lethal game of survival. Which she must now play to save herself and her beloved state. As unpredictable as gunpowder, will she choose to seek Francis's heart, or his life? Or both?