Rafid Ahmed Alwan al-Janabi is one of the most important people in the 20st Century, but most people only know him by his CIA codename: "Curveball." Mr. Janabi was a CIA informant whose information helped lead the nation to invade Iraq and begin one of the costliest wars in US history. Curveball makes his first public appearance in a two-part BBC documentary entitled "Modern Spies." The documentary presents a complicated character aware of the implications of his actions but unwavering in his reasoning. Michael Rudin, who produced the series, explains what it was like to speak to the man who helped bring two nations to war.