At Saratoga National Historical Park stands a monument to a wounded left leg with no name carved on it. That nameless hero is Benedict Arnold. This episode is a psychological autopsy of America’s most infamous traitor, tracing the financial, social and physical grievances that carried him from battlefield brilliance to treason.

We cover his family’s collapse after a yellow fever outbreak and his father’s public disgrace, his tactical genius at Valcour Island, his clashes with Congress and Horatio Gates, the shattered leg at Saratoga, and his court-martial while commanding Philadelphia. Then we follow the West Point plot with Peggy Shippen and John Andre, and the strange chain of events that exposed it.

• How a book cipher based on Blackstone’s Commentaries hid Arnold’s negotiations
• Arnold’s demand for 20,000 pounds and his sabotage of West Point’s defenses
• The splinter in a British captain’s nose that left John Andre stranded
• Arnold’s raid on New London and his bitter exile in London
• Why Arnold might be remembered as a founding martyr had he died at Saratoga