Criminals are not inhuman. They don't emerge with genetic mutations. They are formed in a peculiar social context and would act differently if born in other environments, with different opportunities. In *The X-Man: A Report on the Soul of the São Paulo Assassin*, journalist Bruno Paes Manso lays bare the hearts of these hired killers, gunmen who, living in a dangerous environment where justice doesn't exist, have taken it into their own hands. In Paes Manso's book, they gain a face and a voice. We are introduced to Wolverine, a handsome young man with a simple diamond earring, dressed in the latest fashion and defying all stereotypes, all our notions of what a killer looks like. A young man who chose this life at 16, avenging the death of a fellow football player, thus crossing the border into a world of very different rules. The journalist also presents the story of Zé Bonitinho—a dark-skinned man with a reputation as a ladies' man in forró dances, earning him his nickname—and that of many others. Man X speaks of conflicts that are still little understood or studied. The perpetrators of the murders are generally known in their neighborhoods and face people equally willing to kill. Most often, they make money through criminal activity, and their circumstances are often no secret to their neighbors. In São Paulo, many who kill and die earn money through robbery, trafficking, and kidnapping. As a result, the animosity and desire for revenge among a defenseless society becomes intense. These criminals are seen as potential threats, but they seek to respect the contract that allows everyone to live peacefully in society. Convinced of the legitimacy of their actions, they see themselves not simply as murderers, but as participants in a dispute in which homicide is one of the strategies used by like-minded adversaries. They almost always fight against people who also kill, in the name of a justice system that uses his values as its benchmark. The research for *The X-Man* was based on interviews with more than 20 killers and the beliefs they revealed during their conversations. Bruno focuses on two themes: their motives for committing murder and the profile of their victims. These candid accounts reveal, at their core, the anxieties, fears, and ambitions of these men, which the author seeks to decipher.