Shot at the same time and shoestring as Santo vs. the Evil Brain, Santo vs. the Infernal Men aka Santo contra hombres infernales presents Santo as an agent assisting the police in tough investigations. For once Santo is actually a police agent, in later films he is usually a wrestler who also fought crime or an Interpol agent who also wrestles as well.
The plot involves an attempt to put a police agent into a drug smuggling ring. Surprise, surprise it all goes wrong and the police agent is in danger! Only Santo can get in to extricate him alive!