In March 1847, the U.S. Navy delivers eight thousand soldiers on the beaches of Vera Cruz. They are led by the army's commanding general, Winfield Scott, a heroic veteran of the War of 1812, short tempered, vain, and nostalgic for the glories of his youth. At his right hand is Robert E. Lee, a forty-year-old engineer, a dignified, serious man who has never seen combat.

Scott leads his troops against the imperious Mexican dictator, General Antonio Lopez de Santa Ana. Obsessed with glory and his place in history, Santa Ana arrogantly underestimates the will and the heart of Scott and his army. As the Americans fight their way inland, both sides understand that the inevitable final conflict will come at the gates and fortified walls of the ancient capital, Mexico City.

Cut off from communication and their only supply line, the Americans learn about their enemy and themselves, as young men witness for the first time the horror of war. While Scott must weigh his own place in history, fighting what many consider a bully's war, Lee the engineer becomes Lee the hero, the one man in Scott's command whose extraordinary destiny as a soldier is clear.