Bayou Moon by Ilona Andrews
Cerise Mar and her unruly clan are cash poor but land rich, claiming a large swathe of the Mire, the Edge swamplands between the state of Louisiana and the Weird. When her parents vanish, her clan’s long-time rivals are suspect number one.
But all is not as it seems. Two nations of the Weird are waging a cold war fought by feint and espionage, and their conflict is about to spill over into the Edge—and Cerise’s life. William, a changeling soldier who left behind the politics of the Weird, has been forced back into service to track down a rival nation’s spymaster.
When William’s and Cerise’s missions lead them to cross paths, sparks fly—but they’ll have to work together if they want to succeed … and survive.