Young Joe is an alien living on Earth. At least that's what his father told him before he died when Joe was eleven. His father unsuccessfully wrote sci-fi stories, and Joe loves sci-fi. He has told that he must not deal with humans, unless they are more than 90 percent compatible with himself. When we meet Joe again, he is 26, and the fantasy keeps him going. But is it a fantasy, or is it real? Joe's life changes radically when he meets a more than 90 percent compatible girl. Can Joe trust himself? Does he know what's real?