Inspired by Alexander Dumas's novel The Corsican Brothers, Alma de acero presents a delightful spin on the classic story of twin brothers (both played by Luis Aguilar) and their contrasting lives. As a singer in a nightclub, one brother has chosen a life of peaceful simplicity; the other, however, has chosen a troublesome lifestyle that leads to numerous run-ins with the law, forcing the vocalist to risk his own life to save his sibling.