Toxic-mutated, man-eating slugs descend upon a small US town, consuming everything human in their path. The town's health inspector, Mike Brady (Michael Garfield), is convinced by the threat, but even as the body count multiplies, the mayor and his businessman cronies won't listen. It's up to Brady to find a solution to end the slaughter and save the town.

Shifting the action from Shaun Hutson's Britain-set novel, "Pieces" filmmaker Juan Piquer Simón writes and directs, following formula all the way. I mean, the hero is virtually named Chief Brody and the upstanding-professional-versus-blinkered-authority schtick was done miles better in Steven Spielberg's Jaws 13 years earlier.

"What'll it be next," scoffs the sheriff, "demented crickets?" He's got a point. Convincing the authorities that there's a shark in the water is a far cry from carnivorous gastropods. But the premise actually works okay – its inherent silliness is a reasonable argument for scepticism, after all.

Slugs: The Movie (to give it its full title) is dumb as hell but not without merit. It's well made and swiftly paced, and there's just enough characterisation to make you care about the community under threat (even if those characters tend to be identified by a single feature: she's a drinker; he's an Englishman etc).

The special make-up effects are good, gradually ramping up in grossness. These little bastards are mean, happy to munch the flesh and the eyes off their victims. There are hints of the Piranha movies in the creatures' swarming nature (although the quality of filmmaking is a step up from James Cameron's cack-handed sequel). But a more appropriate comparison might be Fred Dekker's equally squirmy Night of the Creeps, which two years prior did a better job of embracing the camp 50s monster movie vibe.

While there are probably too many scenes involving people walking into offices and receiving phone messages (if ever there was a movie to be fundamentally altered by cell phones, it's this), the narrative structure is solid, and decent production values allow for a surprisingly exciting and large scale ending – even if Brady's final plan is preposterously reckless.

Slugs delivers few surprises, simply transposing its icky threat into a stock plot for a genre not used to posing such slow-moving threats. But it's fun and disgusting and worth a go for the post-pub slot in the run-up to Halloween.