The Shiloh Sisters
Kilian, Michael. The Shiloh Sisters. New York: Berkley, 2003.
Union spy Harry Raines and his sidekick Jack Tantou make their way from New Mexico to Corinth, Mississippi, where they are set by General Grant to solve the mystery of two sisters -- wives of officers on either side -- who have somehow managed to get themselves murdered in the wake of the battle of Shiloh.