The first chapter gives a whirlwind introduction to Juan Manuel Rubio, a former Colonel of the Mexican Revolution, now an exile and a gunslinger. He turns up in Juárez, a city that he twice helped to liberate in bloodier days. There, he poaches a young prostitute from another client, shoots her pimp when he protests, and gets speedily arrested.

The arresting lieutenant recognizes him as an old friend and ally of his boss, General Hermilio Fuentes. Reunited, Fuentes and Juan Rubio talk over what has become of Mexico since the revolution. Juan Rubio explains that he shot the pimp because he was a Spaniard, a colonizer. The corruption and dishonor that many heroes of the revolution have fallen into appalls him, and he even challenges his old friend Fuentes over his willingness to turn a blind eye to corruption; he shows himself to be a proud, patriotic person, with strong ideas about manhood. Fuentes sadly tells him that this is what it is to grow old, and helps him create a plan to evade arrest by fleeing north across the border.

Juan Rubio takes a job running cattle, and determines to take part in a plan to assassinate the corrupt President.