The folks of mountain town Devil's Crag are unsettled and no wonder, for there has been a spate of livestock killings and mutilations recently which have escalated into the deaths of a couple of locals, and the Sheriff (Bob Steele) is no closer to solving the crimes now than he was when the first one was committed. He does have a suspect in mind, however, and it's not Indian Joe (Billy Dix) who has a grudge against the white man, nope, the Sheriff thinks local archaeologist Wayne Brooks (Ed Kemmer) is behind them, and just needs the evidence to put him away for good. Yet the truth is something quite different...
In the nineteen-fifties, as far as Hollywood was concerned anyway, the scary movies were the science fiction movies, and there was an abundance of creature features where the monsters could be explained by science and lots of it. There were exceptions to this rule, and Giant from the Unknown was one of those, though it was a horror that posed as sci-fi to be more accurate, with the monster in question having a scientific explanation by dint of the fact it was scientist investigating it: Kemmer, genre stalwart Morris Ankrum as a professor, and his daughter Janet (Sally Fraser) for good measure.
Janet, it had to be said through no fault of her own, was stuck in the stereotype role from minute one, purely present to make the coffee, wash the dishes and prepare the beds when the trio were out camping, seeking Conquistador treasure that had been long-buried, or so the Professor believes. There was more to it than that, for an actual Conquistador named Vargas was buried too, and reanimated with lightning and the "special rocks" he was buried under every time there was a storm: you guessed it, he was responsible for the murders and slaughters, as Janet would discover come the inevitable scene where she was slung over his shoulder.
Oh, she screams, too, in case you didn't get the message - not every heroine of fifties fantastical fiction was this useless, honest, but you would be hard pressed to find one quite as fitting all the clichés as Janet. This could be pretty amusing in its crass fashion if outdated attitudes tickled your funny bone, but the main problem here was shared with plenty of this decade's lower budget efforts, that all the business in between the battling of the monster was almost entirely disposable and frankly a bit of a slog to get through, especially if you could not be guaranteed something entertaining after the endurance test passages the first half consisted of. Even then, past that midpoint mark there were longueurs.
Kemmer was a bland hero, not called on to have any more personality than Janet who he equally predictably gets into kiss-up situations with. The only really interesting thing about him was that he was accused of crimes he did not commit, and this did not contain much suspense as we were all too aware the Sheriff would twig Vargas was the murderer before long, which he did when he clapped eyes on the brute himself. This hulk was played by the towering Buddy Baer in a typical role, though intriguingly his makeup was designed by Jack Pierce who had conjured up the looks for all those classic Universal horror monsters; alas, this would not go down in history as one of his finest achievements, and it was a pity after such a huge impact on horror he was reduced to this barely there B-movie. Nevertheless, there were occasional diversions when Vargas went on the rampage, throwing large rocks and pushing over trees, but there was not so much as an inkling of a surprise how this played out: basically a Bigfoot movie before its time. Music by Albert Glasser.