Agent Joaquín recalls his latest mission while lying wounded in an ambulance: Joaquín has infiltrated a band of smugglers. When the villains learn the truth about him, they kidnap Joaquín’s fiancée. Santo comes to her rescue and fights the band.

In his second cinematic excursion, shot and released at the same time as Santo vs. The Evil Brain, our masked hero flexes not only his muscles but also his ingenious wits. As Santo deciphers coded messages and intercepts secret rendezvous, an intriguing atmosphere of espionage lingers in the air.