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.
"The cemetery of Guanajuato is a real tourist attraction. There, mummies are exhibited (...) The guide enjoys scaring tourists with terrifying legends. One of them tells that the largest mummy, belonging to a gigantic 2.20-meter individual, was not dissected by natural procedures or embalmed by human hands. Its almost perfect state of conservation (except for the face) is due to the fact that the above mentioned made a satanic pact. The giant was in the past century a professional wrestler, known as "Satan" because of his proclivity towards the dark. Satan fought against an ancestor of Santo, the Silver Masked Man, and was defeated. But he swore vengeance, assuring that he would return from the dead just 100 years later, to take revenge on the Saint's successor and his followers.
(...) This is one of Santo´s best known films, and paradoxically the Silver Masked Man is not the protagonist. His role is quite secondary; he doesn't appear until well into the film, being Blue Demon and Mil Máscaras the wrestlers with the greatest acting weight in the film.
(...) The revenge of a being from another era, who was defeated by an ancestor of Santo and now seeks revenge, is a recurring theme of the saga. An analogous plot is found in "Santo against the Vampire Women" (Alfonso Corona Blake, 1962).
(...) Without a doubt, "The Mummies of Guanajuato" is one of the most remembered and enjoyable films in Mexican wrestling."