Are terrorists mad, bad, or a combination of the two? It takes a special sort of mind to prepare to kill large numbers of people on the basis of a highly speculative political analysis. Orsini’s remarkable book gets as close as any to understanding this sort of thinking. Although it can be hard going at times, with dollops of pedantic sociology, the book is sustained throughout by stark and candid quotes from past members of the Red Brigades, an Italian terrorist group active in the 1970s. The Red Brigades were animated by a simplistic Marxism, and Orsini is at pains to stress the importance of ideology in legitimating terrorism. It is not hard to recognize similar tendencies in other groups: the conviction that the group has a vanguard role that enables its members to see the struggle with unmatched clarity, the belief that unswerving devotion to the cause creates a right to do anything for it, and a readiness to deny the humanity of all opponents. Although Orsini does not compare his leftist terrorists with Islamists, he does show elements of the same mindset in past Marxist groups and also in contemporary neofascists.