Book Five of Merlin's Descendants.

1763: all of Europe is at war with each other and the Turks are storming toward Vienna. The magical protection of Britain requires that Georgina Kirkwood, a potential Merlin, leave the secret Pendragon Society and disguise herself as man to fight for England. Wounded and no longer able to carry a sword, Georgina is recruited by the King as a spy in the American Colonies. Transplanted to a land and people vibrant with life and ideas, she begins to question her loyalties. Only her love for Major Roderick Wythe gives her the grounding and stability to work with Ben Franklin, Thomas Jefferson, Sam Adams and many other notable leaders to discover what being the Merlin truly means and to determine who she is protecting from whom.