Based on true events. At the end of the 19th century, Ignacio de la Torre married the daughter of the president of Mexico, Porfirio Díaz. Ignacio leads a double life: he rises in the traditional world of politics while being a member of a clandestine society. The delicate balance holds until he meets Evaristo, the 42nd member of the society. Secrets come to light and it all culminates in a scandalous police raid at one of his parties, also known as the dance of the 41.