I’m not sure what director Tom Six intended when he used the tagline “”their flesh is his fantasy”” to advertise his horror film, “”The Human Centipede (The First Sequence),”” but it could double as a tag for a porno. It would be fetishist torture porn about a man who stitches people together from mouth to ass. Tom Six is probably a sick dude; however, if his work is any indication, he is not a frightening one.

“”The Human Centipede”” has a familiar start, with Jenny (Ashlynn Yennie) and Lindsay (Ashley C. Williams) as American tourists in Germany who become stranded in a remote area late at night during a storm. Predictably, they trek through the woods in stilettos to get help.

The girls reach the home of Dr. Heiter (Dieter Laser) after much wandering and high-pitched whining. Heiter, a reclusive former surgeon in a minimalistic house of creepy art, offers them water. But that’s not all. Turns out the guy keeps rohypnol in his kitchen like after-dinner mints.

Heiter holds both girls and a man named Katsuro (Akihiro Kitamura) hostage and explains he was once famous for separating conjoined twins. Now, he plans on building them. Cue melodramatic music. His victims will be Siamese triplets — a human centipede. He has diagrams. Katsuro screams obscenities in Japanese. It’s almost funny in a surreal way.

The plan is so sinister that it seems too ridiculous to take seriously.

Heiter sews the trio together, placing Jenny in the back, Lindsay in the middle and Katsuro as the head of the centipede. The surgery is surprisingly subtle, just Heiter pulling out his victims’ teeth, then slicing through their skin. It’s less visually gruesome than the average episode of “”Grey’s Anatomy.””

To be fair, there must be very little dignity in a role where you spend the entire second half of the film with your face in someone else’s anus. But, up until the point when they cannot speak, Yennie and Williams sound so forced that they become one-dimensional caricatures of other horror flick victims. Only Laser plays his part well — and alarmingly so, because no man should be that good at being a ruthless sociopath. But his talents are wasted. Heiter practically jumps and claps when Lindsay is forced to swallow Katsuro’s excrements. This is absolutely revolting, but not frightening.

The trailer is a dare to viewers to see how much they can bear, but gives away the whole plot. Already crippled by predictability, the film is further hurt by forcing the viewer to constantly straddle gross-out shock and genuine fear. Audiences will be left underwhelmed, albeit definitely nauseated. The story devolves into they-eat-each-other’s-poop nonsense so quickly that the film alternates between childishly silly and incredibly boring. While not for those with a weak stomach, “”The Human Centipede”” is entirely forgettable and ultimately, a disappointment.

Final Grade: C-