In the isolated town of Prosperity, Ariz., a mining company heir (David Arquette) and a local sheriff (Kari Wuhrer) learn from her son (Scott Terra) that a chemical spill has caused an array of exotic spiders to grow to enormous size. Feasting on pets, livestock and eventually residents, the aggressive beasts wage an assault on the dozens of survivors, who take refuge in a downtown mall.

If Prosperity had a drive-in movie theater, this is where “Eight Legged Freaks” would likely play. And by no means is that an insult.

Eileen Ryan, left, and David Arquette star as potential victims in the comedy thriller Eight

With a tagline that proclaims “The biggest, nastiest, mutant spider movie of all time!,” the film is perfect goofy fare for the summer season. It’s well-paced and mindlessly entertaining and particularly aware of that last detail. There’s a level of post-modern irony to the project, but not enough to change the fact that this is just as much a ’50s nuclear-spawned sci-fi thriller as it is a campy homage to a ’50s nuclear-spawned sci-fi thriller.

“Freaks” has a creation story about as plausible as “Them!” or “Tarantula” or any of the giant bug movies that became associated with Cold War paranoia. Similarly, it features a cast as befittingly inane as those pictures.

Arquette? Wuhrer? The only star missing is Tom Arnold to complete the lame-brained trifecta.

Yet somewhat ironically, “Eight Legged Freaks” owes more to 1986’s “Aliens” than it does the whole catalogue of material from the Eisenhower era.

There’s the gun-toting female heroine, the creatures who cocoon their victims alive and the showdown with the big mama of the brood. There’s even a scene where the armed humans invade a tunnel nest but are unable to use their weapons for fear the spark will set off an explosion.

Admittedly, none of the material is all that original, regardless of what decade it seeks to pilfer. For a comparison to a superior work, look no further than 1990’s similarly themed “Tremors,” which actually reinvented the dormant genre with its tale of carnivorous desert worms. (That action took place in Perfection, Nev., sound familiar?) While “Eight Legged Freaks” isn’t quite up to the level of that drive-in classic, it likewise manages to juggle fun/danger and laughs/horror.

What separates this film from its predecessors of yesteryear is the CGI technology now available for special effects. Moving beyond the old days of superimposing exaggerated-scale shots of actual spiders into scenes with people, “Freaks” uses every digital trick in its $30 million arsenal.

Great detail is given to the look of these eight-legged adversaries. Their movement and weight seem to match their relative size during hundreds of creeping confrontations. Most of the combat sequences as ludicrous as they are appear about as authentic as enormous mutated arachnids assaulting humans can look.

Unlike other “giant spider” movies, “Freaks” benefits from having a variety of the fiends to choose from, each one presenting their own problems for the defending humans. There are jumping spiders (who chase teens fleeing on motorcycles in the flick’s most exciting sequence), trap-door spiders and a Tarantula that is the size and imperviousness of a Panzer. Then there are the orb weavers who mummify victims with webbing before “drinking” them.

It’s all horrifically grotesque for a film billed as escapist entertainment. The pure malevolence of the movie has to be appreciated on some level (not even one of the family pets lives to see daylight). It’s commendable that the filmmakers portray the spiders true to their nature without trying to anthropomorphize them. After all, arachnids are free from the restrictions of human morals. They just do what they do to eat, reproduce and survive.

Good thing they’re ordinarily at a size where a shoe or rolled-up newspaper is all that’s necessary to dispatch them.