The year is 1648 and life in Venice is serene for Isabella Hawkins and her friends Willem, Al-Qasim and Signora Contarini. Together they publish fine books like the controversial encyclopaedia, the Sum of All Knowledge. When a new Inquisitor declares war on free speech however, they are forced to flee across the seas to the wondrous capital of the Ottoman Empire, Constantinople, which is ruled by the infamous Sultanate of the Women. Old friends and new, including the boy Sultan and his sister, welcome them to the world's greatest city. But Isabella is soon entangled in poisonous palace intrigues, while her friends secretly play perilous games of their own.