Socialite Peggy Shippen is half Benedict Arnold's age when she seduces the war hero during his stint as military commander of Philadelphia. Blinded by his young bride's beauty and wit, Arnold does not realize that she harbors a secret: loyalty to the British. Nor does he know that she hides a past romance with the handsome British spy John Andre. Peggy watches as her husband, crippled from battle wounds and in debt from years of service to the colonies, grows ever more disillusioned with his hero, Washington, and the American cause. Together with her former love and her disaffected husband, Peggy hatches the plot to deliver West Point to the British and, in exchange, win fame and fortune for herself and Arnold.