The Courier's Wife. SECRETS OF THE BLUE AND GRAY series featuring women spies in the American Civil War, #1

She joined the Pinkertons to serve her country. She didn't plan on the secrets, or the feelings, that followed her behind enemy lines. Washington City, 1862. Hattie Logan has left her privileged Indiana family behind to become one of Allen Pinkerton's female operatives, steaming open Confederate mail and hunting for coded messages that might turn the tide of the war. She's good at it. But when a routine letter exposes a secret about her own father's dealings with the Confederacy, Hattie makes a desperate choice, volunteering for the most dangerous assignment the agency has to offer.
Posing as the wife of British-born courier Thom Welton, Hattie crosses into Rebel-held Richmond, where their task is to gather intelligence on a Confederate spy network and flush out a double agent whose reach extends into Hattie's own past. The cover story requires a convincing marriage, so Thom slides a ring on her finger in a carriage rolling south. Surrounded by Confederate sympathizers, hiding her family's betrayal, and trusting a man she barely knows with her life, Hattie discovers that the distance between a feigned marriage and a real one may be shorter than she ever imagined.
Inspired by the true story of Pinkerton operative Hattie Lawton, who posed as a fellow spy's wife in Civil War Baltimore and Richmond, The Courier's Wife launches the Secrets of the Blue and Gray series. Following women spies through the battlefields, prisons, and back channels of the American Civil War, these four novels blend slow-burn romance with page-turning spy craft for readers who love stories of real women written out of history.
If you've been looking for a Civil War series to lose yourself in, this is where to start. Clean historical fiction; romantic tension without explicit content. Book One of the Secrets of the Blue and Gray series