In the 1970s and 80s, there seemed to be some competition between low-budget horror movie directors to see who could transform the most unthreatening of creatures into a lethal force. Leading the pack was Blue Sunshine's Jeff Liebermann with his 1976 Squirm, in which downed power lines transformed ordinary earthworms into carnivorous monsters. Predating that was George McCowan's 1972 Frogs, which co-starred a down-on-his-luck Ray Milland, and William F. Claxton's unintentionally hilarious Night of the Lepus, in which a small town is terrorised by a posse of giant rabbits. I'll also give an appreciative nod to Jeannot Szwarc's 1975 Bug and its killer cockroaches, though as far as I'm concerned those particular animals are horrible by default. But these ones can start fires!

A little late to the party was Juan Piquer Simón's 1988 creature feature Slugs, in which one of nature's yuckiest garden creatures (try treading on one barefoot if you somehow think otherwise) has been transformed into a slimy gastropod that feeds on human flesh. Mind you, the early signs are that the title is a big fat lie and that the monsters are actually ferocious piranha, since they don't slither out of the cabbage patch but pull a teenage kid off his boat and into a lake by his dangling feet. This confuses the crap out of his girlfriend, though this is someone who, after presumably having watched her beau unpack and assemble his fishing rod, bait the hook and cast the line out into the lake, says, "So you weren't kidding when you said we were going fishing, huh?"

Following a brief but rather nicely done title sequence, a loveable drunk is nearly run over by a carload of local rowdies, then heads home with his dog, reads aloud the words "eviction notice" and "last warning" in an expositional voice from a letter he picks off the floor and contemptuously screws up, then grabs a drink and lies down on the sofa. What he doesn't realise is that there the cellar in which he tosses his old food is infested with slugs. The sort of slugs that go swimming in lakes and grab unsuspecting fishermen, no less. The next day his half-eaten body is discovered by grouchy Sheriff Reese and County Health Inspector Mike Brady, whose drive to the old man's house is accompanied by what sounds like the jaunty title music from an unproduced 70s American TV cop show.

Before Mike can figure out just what is responsible, the slugs make their way into other properties in the town. One crawls into the glove of grumpy gardener Harold, whose wife Jean plonks a plant whose leaves are covered in small growths in front of him and barks "I would just like to know what are these," yet when hubby informs her that they are slugs' eggs her immediate response is, "I don't care what they are!" But you just said... Oh, never mind. When Harold puts on his glove, actor Juan Maján is required to wrestle with it as if there really is something screamingly painful inside that just won't let go of his fingers, and frankly he does a pretty good job of selling this as real. This culminates in a pain so intense that he is forced to cut his hand off with an axe, which is followed by an explosion spectacular enough (superb model work here) to suggest that the film had a larger budget than surface detail otherwise suggests (it did, as it happens). More unpleasant by implication is the salad that the flirty and heavy-drinking Maureen prepares for her hotshot businessman husband David. We can only guess what the big black slug in the lettuce she sliced up starts doing to David's increasingly troubled insides, at least until a harem of worms explode out of his eyes and face at a business dinner. Yep, if you came for the gore, you'll be a happy lepus. If you came for the acting and smartly written dialogue, however...

A supremely naff script aside, part of the problem here lies in the fact that Slugs is a Spanish-American co-production, and a good many of the actors are Spanish and have been redubbed in post by anonymous others. The awkwardness of their line delivery makes it easy to spot who these unfortunates are, but even without that the sometimes audible shift in sound quality from location acoustics to sound booth mics should tip you the wink. Sometimes expressive but too often stilted, this post-dubbing hits an unintentional comical peak – one that the filmmakers themselves admittedly can't have seen coming – with school science teacher John Foley, whose terribly British replacement voice sounds for all the world like he's been dubbed by Austin Powers. Smashing.

Plot development follows the standard sub-genre pathway, with the attacks increasing in number and Mike theorising a cause that those with the authority to help him immediately dismiss as preposterous. Mind you, even our Mike is sometimes not the sharpest stick in the bundle. When his teacher girlfriend Kim finds some big slugs in their garden she suggests they could try throwing salt on the buggers, to which Mike eagerly responds, "That's a really good idea!" Yet a short while later when the creatures start dropping out of a tap in Kim's kitchen, Mike responds instead by giving them a few playful taps with a frying pan. In the end it's Austin Powers who comes up with a solution, one that will not so much kill the little buggers but blow them and half the town's sewers to kingdom come, which at least delivers an appropriately explosive climax.

Yet on a technical level Slugs equits itself rather well, and genre devotees will doubtless delight in the gruesome bloodiness of slug attacks themselves. The star of the show is a scene in which a young and randy couple, after engaging in a bout of energetic and surprisingly graphic sex, get up to find the bedroom floor carpeted in slugs, which they foolishly step on with horrible results – if the sight of the male half of this post-coital couple trying to pull out a slug that has buried its head in his foot doesn't make you yelp (it did me), then just wait until his naked and panicky companion slips over and falls face-down into this squirming carnivorous mass.

Slugs is not a film I feel inclined to champion as a previously overlooked, low-budget gem. Too many of the performances are either stilted or a little hammed up, the witless script has no ear for conversational or even confrontational English ("You ain't got the authority to declare Happy Birthday!"), and the dubbing is clumsy and occasionally comical. But if you can stomach all this or actually find it rather fun (think 70s giallo at its most linguistically daffy), the film moves at a lick, is technically sound, and has some impressive physical effects and enough gleeful nastiness to put an appreciative smile on all but the most demanding gore hound's face.

A crisp, colourful and sparkling clean 1.85:1 HD transfer that sings an appreciative song to Julio Bragado's cinematography and particularly his night-time and underground lighting. The beefy black levels are consistent throughout, the contrast nicely balanced and the colours vibrant when they need to be. Lovely job.

The Linear PCM 1.0 mono soundtrack is also in fine shape, boasting a better dynamic range than I'd normally expect from a single speaker track (then again, the film was made in 1988, so it really should have). It's especially kind to Tim Souster's jaunty if occasionally comically inappropriate music score.

Here's Slugs in Your Eye (7:39)
An interview, filmed in Madrid and conducted in Spanish with English subtitles, with actor Emilio Linder, who does rather a good job as David in spite of the dubbing. It doesn't run for long, but Linder covers his early work, meeting and collaborating with director Juan Piquer Simón ("one of the greatest Spanish filmmakers"), and his work on Slugs, which he still holds in high regard. Good on him.

They Slime, They Ooze, They Kill! (10:46)
An interview, also recorded in Madrid and conducted in Spanish with English subtitles, with special effects artist Cartlo De Marchis, whose work is definitely the star of the show here. He's also a big fan of director Simón, whose handling of effects he rates above Spielberg's, and De Marchis has worked with them both. Tellingly, however, he does admit at one point that "Piquer didn't have a great talent for directing actors." There's quite a bit on the creation the exploding head in the restaurant death scene, and when it comes to working with animals his advice is that, "A dog is easier, but a cat is always difficult."

Invasion USA (11:52)
And while we're in Madrid with a Spanish translator, we also have an interview with art director Gonzalo Gonzalo (and that's not a typo), who recalls first working with Simón on commercials and what fun he had working on Simón's films. There's some interesting detail on the climactic sewer sequence and the bedroom slaughter, enough to suggest that the term 'art director' also includes some responsibility for physical effects. And Simón was apparently very picky about quality of his effects work – if they weren't up to scratch he'd apparently either dump or reshoot them.

The Lyons Den (21:00)
An interview and tour of the Lyons locations with production manager Larry Ann Evans, who comes across here as the happiest person alive – I've spent evenings with people spaced out on magic mushrooms who didn't smile and laugh as much as Evans does here. There are some interesting stories about the production and director Simón, with whom she clearly loved working, and it's here that I learned that the budget was around a million dollars, big bucks for a Spanish horror film of the day.

Trailer (1:37)
"First they got into the water system, now they'll get into your system!" this solid enough sell for the film amusingly proclaims. Surprisingly gory, too.

Audio Commentary with Shaun Hutson
Impressively moderated by disc producer Michael Felcher, this interview with Shaun Hutson, the English author of the novel on which the movie is based, is an absolute blast from start to finish. Hutson is a delight, being upbeat, down-to-earth, cheerfully self-deprecating and without a whiff of pretension about his craft (he started young and has written over 70 novels under various names). While he does have an affection for the film and is happy to defend it against its detractors, he's also not shy about shooting holes in the (many) elements he regards as ineffective or even preposterous, particularly when recalling his first viewing of the film with an audience of friends and associates. I was intrigued to learn that there are in fact three species of carnivorous slugs in the UK alone and that the infection that eats away at David in the film is based on an actual condition contracted from slug slime (he even knows the Latin name by heart), and I genuinely applauded his anger at the damage the Twilight books and films have done to the horror and particularly vampire genres. He also has some sound advice for any author who sells the film rights to one of their books: "You sell the rights, and really, if you've got any sense, you then forget everything you've ever written and realise that what turns up on screen is going to bear no resemblance at to what you've created on a printed page." Felcher is an excellent feed man and the interaction between the two makes you wish you could be part of their lively conversation. This may well be the most entertaining commentary track I've listened to all year. Even if you don't enjoy the film this is well worth a listen. Superb.

Audio Commentary with Chris Alexander
This typically lively audio commentary by ex-Fangoria editor and co-founder of Delirium magazine Chris Alexander is both a delight and a personal nightmare for someone who finished his review before throwing this on. As the commentary unfolded, I felt my face slowly falling as just about every point I'd picked up on and included in my review was then made by Alexander, plus a few I considered but elected to leave out. When he got on to John Foley's English-accented dub I was silently begging him not to make the Austin Powers connection (I was so chuffed when I realised that) and thus heaved a huge sigh of relief when he did not, only to then be flattened during the climactic scene when that suddenly dawned on him as well. And it's such a great track, with Alexander bristling with enthusiasm for a film he's still happy to pick sizeable holes in and including some intriguing readings of elements that I've no doubt Hutson – who claims there is no subtext at all in his novels – would dismiss as coincidental. A terrific listen, at least if you've not just had your own carefully chosen words soundly gazumped.

Also included with the release disc is a fully-illustrated collector's booklet featuring new writing by writer Michael Gingold, but this was not supplied for review.

A guilty pleasure, perhaps, but one I've already revisited twice since the review disc landed on my mat, drawn back to savour the effects and quietly titter at the dubbing, but each time with a degree of genuine affection for this oddly entertaining creature feature. Many will scoff and they're free to do so, but if this is your bag, baby, then Arrow really have done right by the film. Great transfer, fine extras, a splendid package all round. If you already have a soft spot for Slugs, you'll love this disc.