In this bewildering and crass science fiction comedy, Jerry Lewis plays Caleb Swain, a wealthy couple's father who must confront his "deformed" alien twins, Wilbur (also played by Lewis) and Eliza, when they reveal their incredible intelligence when their heads are touching. The film is loosely based on Kurt Vonnegut's novel Slapstick, but has been stripped of its thought-provoking themes in favor of slapstick humor and absurdity. When the twins' telepathic connection is revealed, their parents must separate them to avoid incest, leading to a series of hilarious misadventures as they try to keep their children from uniting again.