Directed by Jose Diaz Morales
According to IMDB there are no writers, therefore probably no script. I guess there was just a loose story.
IMDB

In this flick we find out that Santo's mask is a family heirloom, passed down through the generations. His costume also has magical properties. We meet the Diabolical Hatchet, a villain from Santo's past (the 17th century).
Pretty good sci-fi action movie from Santo. The sets are classic horror movie type sets, with fake spider webs and shit like that. This movie is pretty fun and out of the three Santo movies I've seen so far is the best.

7/10