A couple of weeks ago, I emailed a director acquaintance of mine to say I was off to a preview of his new film. After that, I explained, I was seeing a movie in which a mad doctor surgically combines three people to make a grotesque, insectoid-style creature. The director, who has some experience in the horror genre, knew exactly of which movie I spoke. “You’re seeing Human Centipede straight after my film???” he responded. “Don’t get them mixed up!”

There was, as it turned out, no chance of that happening. Actually, it is hard to image Human Centipede, which opens April 30, ever getting confused with any other film. Why? Well, for one thing it is, as previously mentioned, about a mad doctor who surgically combines three people to make a grotesque, insectoid-style creature, which is not a plot twist you find too often in the filmography of, say, Sandy Bullock. And, for another, it is without question one of the most disgusting horror films ever made.

Human Centipede stars Ashley C. Williams and Ashlynn Yennie as a pair of fun-hungry Americans who seek refuge at the remote house of a surgeon, played by Dieter Laser, after their car gets a flat in some German woods. To say that Laser’s character is sinister is not to over egg the pudding. The guy has “psycho” written all over him, even when he’s not gazing fondly at a photograph of three dogs who have been attached mouth-to-rump. Before you can say, “Just what the Sam Hill is going on here?,” Laser has drugged our two heroines and begun the process of turning them and another unfortunate, played by Akihiro Kitamura, into, yes, a human centipede.

I’ll spare you the details of how he accomplishes this feat — even if the film itself most definitely does not. I’m also going to pass over describing the consequences of three people sharing a single alimentary canal, though those with a basic knowledge of biology and a strong stomach will probably be able to work those out for themselves. Suffice to say that, at the screening, the groans and moans emitted by the onscreen characters were almost matched by those of the viewers, including myself — and I’m someone who has happily sat through every Saw and Hostel movie.

What makes matters worse — or, arguably, better — is that Human Centipede is no shoddily-constructed piece of witless schlock. Laser makes for a terrific villain and Dutch director Tom Six has put together his nightmare yarn with Cronenbergian care and precision. He may also, it appears, be planning a sequel, given that the full name of the movie is Human Centipede: First Sequence.

Is that a promise or a threat inherent in the subtitle? Judge for yourselves — and report back — after daring to check out the trailer below. But you really can’t complain that you haven’t been warned.