A man comes to a western town willing to discover the perpetrators of the robbery of a bank, where a significant amount of gold disappeared and witnesses were cruelly murdered. One of the thieves is now getting rid of the accomplices, using some deadly snakes that only seem to obey him.

Rod Cooper, an American agent of the CIA, is sent to Paris to discover if colonel Segura, head of a clandestine organization which proclaims itself anti-Castroist, is playing a double game at the expense of the United States. He first tries to make contact with Ms Beckett, who should tell him. Segura's intentíons, but the woman is found killed. Subsequently, Rogerson, another American, presents Cooper to Segura himself and so Rod can enter his organization. Here he discovers that the colonel tries to attract a certain number of Americans to use them in an attack against the president of a state of southern America and thus promote communist expansion. Segura soon discovers Rod's real identity and tries to get rid of him; but the agent manages to reverse the situation and kills Segura in a shoot-out.