La noche de los asesinos

The label "thoroughly average" is borrowed from the Aurum Horror Encyclopaedia and, for once, describes the movie very well.

That does not imply that the movie is without interest. There are nice decors and several interesting scenes, e.g., a man is buried alive with only his hands, which are tied to the back, sticking out of the ground like a cry for help or a women is tied to the rocks and left to the tides. Of course, the movie features also Franco's usual dilettantism such as badly focussed shots.

All in all, it is worth a try. No suspense or blood, though. So, watch it only if your are fully awake.

The already quoted horror encyclopaedia contains a plot summary which differs slightly from what I have seen. This could mean that, as so often, there exist several different versions of the movie.