Androids Mother and Father flee Earth to settle on the planet Kepler-22b and start a family with six human embryos; 12 years later, only one child, Campion, remains; a spacecraft carrying humans presents a threat for Mother to confront.

After her confrontation with Marcus and the Mithraic, Mother takes five of their Earth-born children to live on the settlement; as she and Father attempt to put the shaken newcomers at ease, Marcus struggles to survive alone on Kepler-22b.

When the Mithraic kids fall sick, Campion suspects Mother is poisoning them and plans an escape; as Mother and Father try to prove their good intentions, Marcus and Sue work to convince the other surviving Mithraic to mobilise a rescue party.

Father tries to teach children to hunt for food; a prophecy seems to come to life for the Mithraics; Marcus and Ambrose face off.

Under Marcus' command, the Mithraic set out to rescue the children; Campion and Paul bond during a hunting expedition with Father; Mother attempts to learn more about her origins; Tempest's trauma continues to haunt her.

After reconnecting with her creator, Mother finds herself distracted by intense feelings, leaving the settlement vulnerable to Marcus, Sue and the Mithraic; as Campion questions his family's principles, the other children's loyalties are tested.