Santo is hired as a bodyguard of an expedition into the Mexican jungle
to find the mummy of Nonoc of the Opaches.
After some of the usual
jungle perils our motley crew actually find a maze of caves, in the
center of which the tomb of Nonoc (who was buried alive for loving a
priestess) is situated, but with profaning the tomb, of course, also a
curse comes true, which is promising death to the descendants of those
who have buried Nonoc as well as those who have opened his grave. So
soon the mummy comes to life & starts killing people - but not only
by skulking around & strangling them in slow motion, this mummy also
resorts to using bow & arrow.
Only young Agapito (Nino Jorgito),
whose gramps was just murdered by the mummy, has some idea on how to
stop the monster - mainly by returning its necklace of death (which
usually keeps Mexican mummies from skulking around) -, but he is caught
by the mummy first, & almost sacrificed, only saved by Santo just in
time, who dukes it out with the mummy & unmasks it in the end,
revealing it to be
no supernatural being at all but Sergio (Eric del Castillo), one
participant of the expedition, who wanted the mummy's treasure all for
himself - this ultimately proving Santo was right from the beginning,
when he claimed "In all history of humanity, no mummy has ever
returned to life".
It's fun to see Santo (masked as ever) in the wild for a change, in a
mix of jungle adventures & mummy horrors.
The actor who played Agapito by the way was Santo's real life son who
would much later become El Hijo del Santo in the ring & a
handful of films, in the 1980's (e.g. Chanoc y el Hijo del Santo contra los
Vampiros Asesinos), the 1990's (e.g. Santo: La Leyenda del
Enmascarado de Plata), and even teh 2000's (Infraterrestre).