The following review is an extract from the book "Santo, the Wrestler with the Silver Mask: A guide to all his films", which is now available on Amazon.
"Dr. Hugo Olvritch, aka Achilles, is a mad scientist with the intention of subjugating the world. The great powers are worried after two strange events: The launch of a rocket and the explosion of a hydrogen bomb on an island. The US, the USSR and other powerful states deny having anything to do with it. International representatives are meeting in a security council with the intention of preventing the outbreak of World War III.
(...)
On this occasion, the Saint plays a role as an international secret agent, in a film that combines the intrigue of the spy genre with science fiction.
At the beginning there is a very long prologue, reminiscent of the one in "Who Can Kill a Child?" (Narciso Ibáñez Serrador, 1977), where a voice-over narrator warns of the dire consequences of the wars, violence and conflicts that have wounded mankind since the beginning of time. The prologue becomes even longer, and numerous inserts, archive scenes about rocket launches, nuclear bomb detonations, etc., are paraded before our eyes.
Santo, the supposed protagonist, takes 20 minutes to appear. He does so in a ring fight against Blue Demon. He must then collaborate with Professor Gerard (and the "world security control") in locating Olvritch's hideout and neutralizing him.
The film was directed by Julián Soler, a director who is extremely interesting for having made two memorable films: "Si usted no puede, yo sí" (1951), a comedy with a script by Luis Buñuel and Luis Alcoriza; and the excellent "Pánico" (1966), a psychological horror triptych (not exempt from black humor in its last segment). On the other hand, this "Santo contra Blue Demon en la Atántida" is predictable and dispensable."