This movie about slugs with teeth that eat people is called Slugs the Movie because it is based on the book, and they wanted to make sure you understood they were connected. There was a second book by the author Shaun Hutson about man eating slugs. Think about that.
The hero of the film is a health worker named Mike Brady. The slugs are very calculated at first, making sure to leave the scene of the crime. Of course, Eagle-Eyed Brady (it is never used in the movie, but I am sure that is what everybody calls him) finds a trail of slime at the scene of the crime.
This may surprise you if you have never seen a nature themed monster movie, but nobody really believes Brady.
This is after a guy rips his face off in a restaurant full of customers because he has slug based parasites in his brain. It was not the fault of the restaurant, his wife made a salad with a slug in it. Anyways, with the help of a scientist, the hero and his small team come up with a chemical to kill all the slugs. They go to the nest, the slugs apparently swim (they attack a guy in a boat on a lake and the devour a guy in a water tank where their nest is) and so the nest is in the sewers.
The cast is pretty stiff, and there are not really any names in the film. A lot of this has to do with the film was main in Spain and there appears to be a fair amount of dubbing. The effects are pretty solid compared to the times. They use shots of regular slugs mixed with fake slugs which has…well, mixed results. Some of the ways they achieved shots is kind of interesting. Slugs is also a very slow paced film, this in spite of having a kill every ten minutes or so.
Arrow Films has released a special edition Blu-Ray which is packed with features. There are several interviews with cast and crew. They are very interesting and informative. The interview with Special Effects man Carlo De Marchis is especially illuminating with behind the scene photos of the effects. De Marchis has worked with Ridley Scott and Steven Speilberg, so he has a strong effects background and shares some great stories. All but one of the interview featurettes are in Spanish and have subtitles, but this really allows the interviewee to not spend time searching for the right English words to express.
The Blu-Ray contains two commentaries, and one is with the author of the novel, Shaun Hutson. This commentary is a lot of fun, and Hutson is quite entertaining. For example, Hutson was hired to write the novelization of the Terminator. After the novel was printed and being shipped, there was a discovery that the rights had not actually been obtained, resulting in someone else writing a novelization of the film. Hutson mentions how when seeing Slugs in a theater, he kept turning to his wife (asking if various scenes were in the book).
Arrow has put together a nice package here that is informative and entertaining, even if the film itself is not amazingly good.