Alex Cox's story of William Walker (Ed Harris), an American soldier of fortune, whose Latin American escapades in the mid 1800s continue to have ripple effects in US policy today. When his wife dies, Walker decides to leave a promising career in politics behind and, backed by banking magnate Cornelius Vanderbilt, travels to Nicaragua to make it safe for Vanderbilt's steamships. However, once there, Walker sets himself up as Nicaragua's president; until the nation decides they no longer want to be ruled by a mad 'gringo'.