The book's central character is Valentine Michael Smith, a human born during the first manned mission to Mars. After being raised by Martians, Mike returns to Earth, where he experiences human culture as any alien would. But Mike isn't a passive observer. Under the watchful eye of his companions and protectors Jill Boardman and Jubal Harshaw, Mike founds the Church of All Worlds in an effort to help humans overcome their fears and jealousies.