It Came from Beneath the Sea, to prove the point.
ICFBTS was the locus of two important firsts for Harryhausen: it was his first movie with Columbia Pictures, where'd he'd work for many years, and his first movie for producer Charles H. Schneer, with whom he'd work even longer. And these two things are both part of the reason that ICFBTS is, frankly, the animator's first "cheap" movie; Mighty Joe Young was made with RKO, a company that new how to treat its B-movies with respect; The Beast from 20,000 Fathoms was at Warner Bros., which at no point in its history was in a position to throw less money at any given project than Columbia could. It would be a mistake to call either of them "prestige pictures", but they were both given a fair pile of resources and expected to perform at a certain level of quality. Schneer and Columbia, though, were apparently looking more to get in with the burgeoning drive-in market and the attendant boom of formulaic monster thrillers. I have never really explored that genre in any kind of systematic way, so I cannot say where ICFBTS fits in chronologically among the multitude of films about giant creatures leveling cities and endangering square-jawed heroes and their ditzy scientist girlfriends. I can say only that it adopts virtually every single cliché of that genre, and where Beast from 20,000 Fathoms - a title better-suited to this picture than to that one, incidentally - seems rigid and trite only because it establishes most of the rules that governed the next half-decade of genre flicks, and it is in fact a very good movie underneath it, ICFBTS seems rigid and trite because it lacks imagination on any but the most perfunctory level.
The film begins with a bombastic bit of narration and an even more bombastic title card that between them establish the idea that mankind's new technology has made it more possible than ever before to explore the hidden quarters of the Earth, and find God knows what there. The technology that gets this particular plot going is a first-of-its-kind nuclear sub, played by a very-much-not-the-first-of-its-kind regular sub from WWII, and here we find Commander Pete Matthews (Kenneth Tobey) and his crew patrolling in the Pacific. With 79 minutes to spare, director Robert Gordon and screenwriters George Worthington Yates & Hal Smith are given absolutely no freedom whatsoever to dick around (say what you will about '50s B-movies: they knew damn well how to get in and get back out in a swift enough running time that you never had a chance to get really bored. Something that 21st Century B-movies, with their un-B-ish $200 million budgets, would be well advised to learn), and so the film devotes just a scant measure of time to setting up the fairly banal characters of the sub crew - none of whom end up mattering as more than the faces we'll see on and off later - before throwing a Big Unseen Something at the boat. A few tricky maneuvers later, and they're free, but they've taken a chunk of animal tissue with them as a souvenir.
This biomatter is extensively studied by Prof. John Carter (Donald Curtis) and his starry-eyed admirer and colleague, Dr. Lesley Joyce (Faith Domergue), and they eventually conclude it is from an unimaginably large cephalopod, one that has been previously hidden in the deepest parts of the ocean and is now out and about in the shallow world because it has been irradiated in H-bomb tests, and its natural prey is apparently able to detect this and evade it. "Some fish have built-in Geiger counters" is Carter's straight-faced and almost word-for-word explanation. The military, of course, doesn't buy it, but sunken ships and vanished swimmers coming across the Pacific and down the U.S. coastline eventually provide evidence that the two marine biologists might be on to something, and they're able to whip together a plan to stop the animal just in time for it to come ashore at San Francisco, where it proceeds to do as giant monsters do and begin tearing apart the most famous landmarks.
Were I to list all the points where ICFBTS takes the most obvious and hackneyed way through its story, I would basically be re-writing its script, but here's a few of the biggest ones: the nuclear-spawned monster (though at least in this case, it's not a simple "nukes make animals big" formulation), frustrated scientists trying to convince the military to see the unavoidable if extraordinarily weird truth, the one-use-only superweapon that ends up misfiring, forcing the heroes to fight the monster more directly, and manfully; a lady! scientist!, with all the agog shock thereby implied; a love triangle between the lady scientist, the utterly male military hero, and the intellectual (and thus at least somewhat feminised) man scientist. At least ICFBTS has a fairly interesting lady! scientist! in Dr. Joyce (though giving her a female name for a surname is distracting; it feels like she's being called "Dr. Firstname" in a patronising way, given that we only hear her called Lesley just a couple of times), who is considerably more steel-willed than most of her species, and even manages to "win" at the end of the film, in a gag that almost seems willing to concede that it's an okay thing to have women in the work force.
Still, that's an awful lot of movie devoted to personal crises - as will happen in these things - and while Domergue is fully able to enliven her above-average part with an above-average performance, Tobey is a perfectly flat, perfectly vanilla actor whose leading man is flawlessly mediocre: not nearly bad enough to tip the movie into the red, not nearly good enough that his appearances onscreen elicit more of a reaction than "eh, wasn't there something about a massive octopus?" Again, 79 minutes really isn't enough time to seriously lose patience with a movie, but there's quite a lot of movie that consists of people talking about the problem rather than actually fighting the problem, and the people doing the talking just aren't that interesting. Nor is Gordon director enough to do much with these scenes other than get through them fast as possible: the movie is shot with a uniform flat, stagey style (the scenes aboard the sub especially), proficient but bland just like the hero. There is one really strange shot in which the camera swings weakly from close-up to close-up, as though they'd run out of time to do three different set-ups by the end of the day, and had to get a whole conversation knocked out now; that all three principals are at this point wearing face-obscuring suits makes the whole thing that much weirder.
Plenty of '50s sci-fi/horror movies have survived being just this mediocre, though; some have survived being a great deal worse, in fact. And it's always for the same reason: a great monster. ICFBTS unquestionably has that, and it's the reason that the movie, despite being completely unexceptional in very nearly every regard is still remembered as a classic of the genre. Harryhausen's giant octopus is, famously, missing two legs; the most obvious victim of Columbia's budget-pinching. But that just adds a sense of hand-hewn charm, in those few shots where it's obvious. From a technical standpoint, it may actually be the weakest thing Harryhausen had done to that point: the composite shots by which the hectapus is seen to be interacting with San Francisco are less than convincing, let's say. But the animation itself is just terrific: the animal's arms each move with slimy purpose, with personality and menace all their own, and its giant midsection has a perpetual look of violent grumpiness. The race to be the best giant killer animal of that decade is a fiercely competitive one, but the octopus can hold its own with the very greatest, both for the quality of the animation and the sense of purpose in Harryhausen's acting. It's a pity that it's not in a better overall film, like his Rhedosaur in The Beast from 20,000 Fathoms was, but given the number of movies like this that didn't pay off with such a top-notch monster, it is easier to forgive It Came from Beneath the Sea its various narrative, cinematic, and psychological failings.