For several years now, Lions Gate has been trolling the world for grisly horror movies to pick up at bargain-basement rates for American distribution, and this claustrophobic subterranean chase movie from England is the latest they’ve landed. “The Descent” is basically a much smaller-scaled version of the recent Hollywood movie “The Cave,” but with an all-female cast of potential victims and creatures that simply scurry about on all fours rather than fly. (Rather cheaper that way.) The strength of the picture is that director Neil Marshall exhibits a keen knowledge of the conventional cinematic horror devices–the oppressive setting, the quick cut, the sudden sound effect, the canny use of light and shadow. Unfortunately, that’s about all “The Descent” has going for it. It’s nothing more than a genre exercise, and it’s hobbled by a variety of fatal weaknesses.

One is acting which could charitably be described as naturalistic and more accurately as amateurish. That certainly applies to Shauna Macdonald, who plays Sarah, a member of a group of daredevil female adventurers whom we first meet white-water rafting in Scotland. Unfortunately, on the way back from the river she suffers a personal loss that leaves her devastated. A year later, buddy Juno (Natalie Mendoza, equally limber but also challenged from the thespian perspective) has arranged a cave-exploring expedition in America. The two are joined by a typically diverse group of comrades, including Sarah’s fried Beth (Alex Reid), punkish Holly (Nora-Jane Noone), old pro Rebecca (Saskia Mulder) and the latter’s half-sister Sam (MyAnna Buring)–all poorly acted, too. After a bit of bonding, the six intrepid explorers head into a cavern which turns out to be uncharted (a nice surprise from Juno), and before long they’re not only trapped in the narrow passages by a cave-in but find a grisly cache of human bones and are attacked by a bevy of strange creatures that, it turns out, feast on human flesh.

That brings us to the second big flaw in “The Descent”–the so-called crawlers that threaten our intrepid heroines and chow down on a goodly number of them. Visual effects in horror movies are overdone nowadays–indeed, the creatures in “The Cave” were way over-the-top–but here the approach is so minimalist that it’s grotesque, and not in a good way. The beasties look like what they are–guys dressed up in tight white-latex suits with faces decked out in war-paint, scampering about on all fours. They look (and prance), in fact, like refugees from a really bad modern dance company. To his credit Marshall tries to limit their ludicrousness by showing them, especially at first, in snippets, but over time he can’t hide their ridiculous appearance. As a result they’re reminiscent of the distinctly unconvincing aliens of the original “Invaders from Mars” or the bargain-basement ghouls employed on the old 1960s “Outer Limits,” and by the close they’re more likely to evoke giggles than screams.

The trajectory of “The Descent” follows the usual formula–suspenseful tight spots, some hair’s- breadth escapes, a few gruesome demises, some acts of courage and others of cowardice, all ending in the escape of one tormented survivor. (Just image an underground “Alien” made on very little money.) You have to admire the skill with which Marshll, cinematographer Sam McCurdy, editor Jon Harris and composer David Julyan have put the thing together, perhaps with a rented camera and some scotch tape, but ultimately it lacks the imagination that would make it seem really fresh. It goes through the paces mandated for this sort of tale well enough, but without ever adding anything new to the mix, as–for example–“The Blair Witch Project” did. Or to put it another way: unlike the cave in the movie, the plot is certainly not uncharted, and mere technique can’t overcome weakness in acting and effects.

At the press screening for “The Descent,” a spooky ambiance was created before the film by having the auditorium in total darkness (flashlights were used to direct reviewers to their seats) and the sound of constant dripping emanating from the screen. It was actually pretty creepy–more so than the actual movie, in fact. So maybe it would be scarier to turn the projector off and keep that water running for ninety minutes. Just a suggestion, lads.