**SPOILERS** The movie "Memorial Valley Massacre" tries to be different from your average run of the mill killer on the loose films and in a way it succeeded it what it set out to do.
The villain in the film a clean shaven cave boy,John Caso, does kill more then half the cast in the movie by the time its over but at the same time you can't hold it against him for what he does. The cave boy we later find out was abandoned by his father and never had a normal childhood. This instilled a deep resentment in the boy for the human race whom he held, together with his dad, responsible for the predicament that he finds himself in: Living in a cave and living off the scraps of tourists who vacation in the valley.
All this killing and destruction would not have happened if it wasn't for real-estate tycoon Allen Sangster, Cameron Mitchell, deciding to build a campground in the valley that the cave boy dwelled in. With dozens of campers in the area the cave boy just went wild, in his hatred for civilized man, going on a rampage killing some dozen of them by the time the movie was over. We have to understand the cave boys frame of mind in what he did. Feeling that the campers represented his father the cave boy took it out on them for what his dad did to him by leaving him out in the woods to fend for himself at an early age.
Besides the interesting and deep psychological aspects, father and son relationship,of the film the rest of the movie was just too hard to take seriously even if you tried. The cave boy not only survived in the wild for some 17 years he also somehow learned how to drive heavy earth moving equipment, like bulldozers, and how to start fires. Not by rubbing two rocks or sticks together but by releasing gas from a gas-tank and then having the unsuspecting victim light a match blowing himself, and anyone within 50 feet of him, to pieces.
The cave boy at first has the local park ranger George Webster, John Kerry, feel that it's a killer bear that's doing all the killing in and around the "Memorial Valley" campground. Together with his assistant Allen Sangster's son David, Mark Mears, Webster sets out to track down the killer bear before he does any more damage. Later when two of the campers bikers Eddie & Leon, Eddie D. & Don S.Fambeau, helping in tracking down the bear instead find the cave boy's home, with scores of human body parts and bones in it, thing really start to get unraveled. The cave boy feeling he's the victim of a home invasion loses it. Mad at what Eddie and Leon did, in stealing his prized skull, the cave boy comes out in the open killing everyone, including Eddie & Leon, that he comes in contact with.
The movie ends on a high note, of sorts, with the cave boy finally finding his old man who in fact, instead of abandoning him, was searching for the confused young man all these years. ****SPOILER ALERT**** The heart-breaking ending has the cave boy, in his efforts to keep people from finding his secret lair, unwittingly do in his old man. All this happens when father and son were about to reunite, after some 17 years, and forget about the past.