An April morning in Baltimore turns bloody and violent as the first Union troops arrive in the border state of Maryland, where adventurer Tom Flynn tries to avoid choosing sides as the War Between the States begins. Quick with his fists and good at cards, he'd much rather spend his time drinking whiskey on the waterfront than being a soldier again. An impulsive act of compassion soon has him running for his life. He ought to know better, but he can't help standing up for what is right. Flynn soon journeys to the Southern capitol of Richmond to save an idealistic Union spy not only from herself, but also from forces who see the new conflict not as a game, but with deadly intent. In Virginia, he has no choice but to join the dreaded Dark Horse Cavalry just in time for the first Battle of Bull Run. The citizens of Washington City have come to watch the battle with picnic baskets in hand, expecting a Union victory. However, in the first bloody clash of the Confederacy against the Union, it becomes clear that this war will be brutal and long. In the midst of the battlefield, Flynn must fight to save the spy, protect new friends, and settle old scores.