Of all the generals on the American side in the Revolutionary War, Benedict Arnold, in the estimation of George Washington himself, was the best. A brilliant tactician, an inspired commander of troops, a field officer of daring and enterprise, he was responsible for stopping a British drive that could have split the colonies in two. He also very nearly conquered Canada by means of a secret overland attack on Quebec in the dead of winter. Yet Arnold was also a traitor, the most notorious in American history, a man who deliberately betrayed his closest comrades and sold out the West Point fortress to the enemy - the British. Why and how this happened is at the heart of this biography, out of which Arnold emerges as a fascinating, tormented figure, a man who could have been a hero and instead died excoriated, hated by Americans and disdained by the British he chose to help.