At long last, I managed to get my hands on Universal's coveted "The Classic Sci-Fi Ultimate Collection" 3-Disc Set and I started off with this film, one of three I hadn't watched before.
Following an embarrassing pre-credits sequence featuring a very dull lecture by an overly-mannered University professor, this turns into a fairly engaging piece of sci-fi in the proved Universal manner (from the "Mummy" and "Creature From The Black Lagoon" series of films). Even so, about half of this early section involving a group of archaeologists who climb a previously irreproachable mountain after stumbling upon relics belonging to a legendary 'lost' civilization is, amusingly, comprised of stock footage (some of it, apparently, from the celebrated German Silent 'mountain picture' THE WHITE HELL OF PITZ PALU [1929])!
Unfortunately, the latter stages when the surviving members of the group (including likable hero John Agar, a regular of Universal sci-fi outings) come face to face with an underground race of albinos and their mutant 'mole' slaves! which bear strong echoes of another fantasy stalwart, H. Rider Haggard's "She", prove incredibly disappointing; curiously enough, this would also turn out to be the case in such diverse, later sci-fi films as THE TIME MACHINE (1960), BENEATH THE PLANET OF THE APES (1970) and LOGAN'S RUN (1976). In fact, those sequences here come off as downright inane at times (virtually Grade Z stuff)! At least, Alan Napier gives a committed 'menacing' performance as the chief villain...
The thing is that the plot does have philosophical/existential interest: the species concerned had somehow survived the Biblical flood and, due to a constant lack of sunlight, have degenerated to their current 'form' (with the notion that above them, there's only Heaven hence, when the 'normal' humans appear, they're mistaken for Gods!). Of course, they still live in the Dark Ages wearing togas and the like and regularly sacrifice 'obsolete' members in their midst by frying them to death. However, we're never told how the mutants evolved or, for that matter, just why a normal and inevitably beautiful girl should turn up among them after all this time (and whom they obviously consider a 'freak of nature'!).
The supporting cast includes Nestor Paiva (like Agar and producer William Alland, a BLACK LAGOON alumnus) as the hero's elderly companion, who's panic-stricken in the presence of this alternate universe, and soon ends up a victim of the 'Mole People' thus exposing the intruders' essential mortality! Though Alexander Golitzen's set design per se is impressive, the low-budget afforded the film is most evident during the very mild destruction of the underground city at the climax; the downbeat coda in which the heroine is stupidly killed was perhaps unwarranted, though.
In the end, I wholeheartedly share the generally-held view that this one's "probably the worst of Universal-International's '50s sci-fi movies" (to quote Leonard Maltin).