The sultans of the Ottoman Empire locked their heirs in a "Princes' Cage" until they might be needed. Anna Barnes, who had made the Sultans' indiscretions the subject of intense study, felt similar walls closing in on her own life. That made CIA operative Edward Stone's offer doubly enticing. It was only later that Anna, knowing all she did of the Ottomans, discovered how much she already knew about Stone and his conspirators.