Respected anthropologist James Krippendorf (Richard Dreyfuss) and his wife, Jennifer (Barbara Williams), bring their three children along during their much-enjoyed search in New Guinea for a lost tribe. The search fails, despite the family's best efforts. After Jennifer's death back in the U.S., James falls into academic stagnation, having spent all his foundation grant money raising the children as a single parent. Scheduled to lecture at a college and fearful of being charged with misuse of grant funds, James concocts an imaginary tribe, the Shelmikedmu, using the names of his children as a basis. He later fakes a 16 mm "documentary" film, casting his children as tribe members and superimposing footage of a legitimate New Guinean tribe so as to enhance the illusion.