An act of treason, a mysterious murder-and Grant's campaign in the West is finished unless the mystery can be solved. The Mississippi Valley, 1863. - The Confederate fortress town of Vicksburg is the lynch-pin holding together the eastern and western Confederacy. Major General Ulysses S. Grant is tasked by Washington to capture Vicksburg, giving the Union complete control of the Mississippi, splitting the Confederacy and dooming it to ultimate extinction. However, there is treason in Grant's army-treason at the highest levels. His most secret plans are being leaked to the Confederacy; plans known only to a small group of high-ranking staff. But a security officer named John Brown has discovered something-something he will not entrust to any of Grant's officers. Instead, he frantically telegraphs for a pre-war friend, Captain Alphonso Clay, to come out West immediately; then Brown locks himself into a riverboat cabin, refusing to see anyone. Clay, a Union-loyal Kentuckian from a wealthy slave-owning family, responds to the call. He arrives at Grant's headquarters to find Brown has been murdered. Accompanying Grant's army on its march, racing the calendar, Clay frantically tries to discover the truth, knowing that if he does not solve the crime, Grants campaign will be at an end and the United States will cease to be.