Does anyone remember this one? A man with a house or maybe hotel near deep natural cavern system (like Carlsbad). A woman shows up (looking for someone that disappeared?), and gets captured (and abused?). The man's wife tells the woman her own story; the man is shown in flashbacks horrifically abusing his wife (mostly psychological abuse, like surprising her with a dead rat on a covered plate). The monster is some kind of primitive human/missing link (?) that the man discovered in the cave. The man has been caring for it and feeding people to it. It's never really shown, just it's glowing eyes. I don't remember the end except that the cave monster is implied to still be alive.
It was a "B" movie from the early 70's, maybe late 60's. Definitely a movie, not TV. It was filmed in color not BW.
