Soon after invading Iraq in 2003, the United States encountered a major obstacle to piecing together a sustainable state -- in the person of a dour 30-year-old Shiite cleric. Muqtada al-Sadr remains to this day a force and a problem for the Iraqis as well as the Americans. Who is Sadr? His cousin (whose daughter he would later marry) the politically active Ayatollah Muhammad Baqir al-Sadr was brutally executed in 1980. Nineteen years later, his father, Ayatollah Muhammad Sadiq al-Sadr, also politically active but in a more subtle manner, was assassinated. With the overthrow of the Baathist regime, it was as if Sadr had inherited a family mission to challenge the other great Shiite families, who had lived safely in exile during Saddam Hussein's rule; to resist Grand Ayatollah Ali al-Sistani's political quietism; and to lead the Shiite masses who had responded to the religio-political message of his family's elders. The veteran journalist Cockburn, who has reported on Iraq since the late 1970s, paints a compelling portrait of Sadr, his family roots, and his role in Iraq since 2003. He depicts a man who is neither a saint, not even a warrior-saint (witness his followers' shameful killing of Sayyid Abdul Majid al-Khoei, of a rival Shiite religious family, or the killings by his militia in Baghdad), nor the fanatical loose cannon often depicted by the media. A driven man certainly, Sadr is also a canny politician in an Iraq that might usefully be compared to Machiavelli's Italy.