Not to be confused with the Boris Karloff film of the same name, or the similarly themed "Contamination" this is another one of those cheapo Italian knock-off's that came out in the wake of "Alien".
The plot of this film however moves the action from outer space to deep underground, focussing on a group of pot-holers who get more then they bargained for when they encounter extra-terrestrial life deep under the Colorado mountains.
In this, Thelma (Belinda Mayne) and her crew of cave explorers are preparing to check out a series of subterranean caves, when news reports start coming in that the crew of a spacecraft, meant to be landing nearby, have simply disappeared. Thinking nothing of it, they climb down into the vast labyrinth of caves and tunnels inside the mountain and begin to explore.
One of them brings along some strange blue rocks he found strewn around the entrance. But soon after descending into the depths of the cave, they discover the blue rocks were no ordinary geological samples, as the plucky pot-holers find themselves being attacked by strange looking, tentacled alien creatures which hatch out of them and quickly grow to enormous proportions.
Trying to escape from the labyrinth of caves, they find themselves getting picked off one by one by the aliens, which can also take over your body and cause your head to explode, as the rest of the team soon find out. But even if they do manage to escape, what awaits them above?
Not bad as far as these cheapo Italian films go, but that's about it. There's a couple of good gore effects, but the action is way too slow. It takes some 40 odd minutes to get to the action, and the scene where the first head explosion takes place took so long you could have grown a beard whilst waiting. The film isn't a total loss. But unless you're a fan of Italian films you might not like this.
Makes an excellent companion piece with the film "Contamination".