Dr. Grace Brown, a government research scientist at ELF (The Extraterrestrial Life Forms Lab), is forced to investigate a number of alleged abductees who claim they have been probed and impregnated by aliens. To punish her boss for this unwanted assignment, Grace brings these "nut cookies" back to ELF for "further study," but the joke is on her when each gives birth to physically varied and undeniably non-human offspring. This new Generation eXtraterrestrial is as eccentric as their diverse Earth parents and initially causes pandemonium in the government, the courts, and the churches, as all try to cope and sort out how to deal with this unexpected new reality. Grace bonds with and adopts a tiny and brilliant alien boy, Charlie, whose mother died in childbirth. The others return home with their Earth parents and try to grow up as normally as an alien can. Nature and nurture collide as these children and their Earth families face issues of race, religion, vegetarianism, politics, social equality, adoption, gender-identity, alcoholism, love, divorce, sexuality, drug addiction, abandonment, and fame. These ultimate outsiders must cope with parental love, sibling rivalries, peer pressure, and try to fit in, stand out, and make their way in the world, a world that is not really theirs. All the while one question is never far from their thoughts: will their absent and negligent space-parents return for them someday? Charlie makes it his personal mission to find out.