Two pretty American girls are on a road trip through Europe. In Germany they end up alone at night with a broken car in the woods. They search for help and find an isolated villa. The next day they awake to find themselves trapped in his terrifying makeshift basement hospital along with a Japanese man. An older German man identifies himself as a retired surgeon specialized in separating Siamese twins. However his three "patients" are not about to be separated, but joined together in a horrific operation. He plans to be the first person to connect people via their gastric system, in doing so bringing to life his sick lifetime fantasy "the human centipede".