Xenogenesis is a collection of three novels by science-fiction writer Octavia Butler. It tells the story of the integration of two species into one collective society. Set in a post-nuclear dystopian future earth, Xenogenesis follows human protagonist Lilith Iyapo as she interacts with and gets to know the alien race of the Oankali. While getting to know the Oankali and working out her personal relationships, Lilith also serves as a leader to the humans that will eventually make peace with the alien race.

The first book, Dawn, establishes the setting and relationship between Lilith and other major characters. Lilith wakes up in an Oankali ship hundreds of years after humankind has been essentially destroyed by war. The Oankali have spent that time colonizing and settling the earth. When Lilith awakens, she is treated as a prisoner on the Oankali ship. The Oankali tell her that her job is to train and help settle humans on the new earth. The Oankali have a biological drive to mix their genetic material with that of other races, creating hybrid offspring and evolving through change. At first, Lilith is reluctant to help. However, she eventually becomes attracted to one particular Oankali named Nikanj. Nikanj is a third-sex Oankali (neither male nor female) and can manipulate genetic material to create hybrid human-Oankali offspring. Their relationship helps Lilith to cope with her new reality, and also makes her more willing to help train and settle new humans. The Oankali then begin the process of awakening new humans. The newly awakened humans don't entirely trust Lilith because she seems to side with the Oankali. The humans don't want to mingle their genes with the alien race, and they feel trapped on the Oankali ship. The humans eventually settle on new earth, but because they distrust Lilith, they don't take her with them. Nikanj uses the genetic material of Lilith's human partner Joseph to create a human-Oankali hybrid. The boy, Akin, thus has three parents: Lilith, Joseph, and Nikanj.

In the second book, Adulthood Rights, Lilith's son Akin comes of age. As both human and Oankali, he understands the needs, drives, and motivations of each race. In Akin's world, humans and Oankali coexist with a great deal of strife and fighting between the races. Some humans have set up a resistance against the Oankali and refuse to procreate with them. Other humans have set up settlements with the Oankali and are on peaceful terms with the alien race. Those who resist the Oankali are stripped of their biological fertility by the Oankali and cannot procreate. Akin is a leader who is on good terms with both human and Oankali communities. He convinces the Oankali to allow humans who resist to settle on Mars. The Oankali grant humans back their natural fertility and allow them to do this. However, the Oankali believe that humans will destroy themselves on Mars, as they did on planet Earth.

The third novel, Imago, follows the coming of age of Jodas, another one of Lilith's children. Jodas is an Oankali-human hybrid who is also a member of the Oankali third sex. Jodas is able to manipulate genetic material and create new combinations of human-Oankali DNA. Through Jodas's eyes, we see the fully developed and evolved human-Oankali world of the future. In this world, both races coexist peacefully, and there is great love, harmony, creativity, strength, and resilience within their genetically diverse population.