Androids Mother and Father settle on Kepler-22b and start a family with six human embryos. Twelve years later, as Mother and Father begin to malfunction, the arrival of the Mithraic, a religious order of surviving humans, presents a threat that Mother has 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 with a mysterious illness, Campion suspects Mother is poisoning them and plans an escape. Marcus and Sue, desperate to get their son Paul back, work to convince the other surviving Mithraic to mobilise a rescue party for the children.

To prove his utility to their family unit, Father tries to teach the children how to hunt. Meanwhile, after the Mithraic make a discovery that potentially fulfils one of their prophecies, a debate about how to proceed ignites a conflict between Marcus and Ambrose.

Under Marcus' command, the Mithraic set out on a deceptive path to rescue the children, and along the way, encounter a fellow survivor from the Ark.

After reconnecting with her creator, Mother finds herself distracted by intense feelings she didn't know she was capable of, leaving the settlement vulnerable to Marcus, Sue, and the Mithraic's swift approach.

Struggling to maintain his clout as leader of the Mithraic, Marcus begins to make decisions that disturb his family, while Mother's ability to see him for who he truly is threatens his power and puts her in a precarious position.

As Marcus continues to embrace his Mithraic devotion, Sue and Paul's distrust in him deepens. Meanwhile, Mother attempts to alleviate perceived malfunctions, Hunter works on a secret project with Father, and Campion and Paul devise an underground plan of their own.

Determined to keep the children safe, Sue grapples with whether or not she can trust Mother. Meanwhile, Tempest confronts her trauma, Hunter continues his attempts to restore Father, and when a new threat arises, the Mithraic begin to question an erratic Marcus.

Paul begins displaying troubling behaviour that leads to a shocking revelation. Sue confides in Mother while Father battles unfamiliar emotions. As Campion questions his place, Mother and Father uncover a distressing secret about Kepler-22b's native creatures.

When Mother, Father, and the children are invited to join the atheist collective settled in the tropical zone, the future seems promising - but their arrival is met with hostility. Meanwhile, Marcus sets out to fill the ruins of an ancient church with Sol's worshippers.

As the Trust tasks the collective with hunting down the serpent, Mother attempts to reconcile her loyalty to the cause with her feelings for her natural-born child. Campion finds himself sympathetic to the creature, while Marcus seeks to find it before the atheists do.

Upon learning that the serpent is a nonviolent herbivore, Mother devotes herself to its protection, while a betrayed Father pours over his new project: the regeneration of an ancient android. Using his mysterious new powers, Marcus rescues a group of Mithraic prisoners.

After the Trust plants a bio-bomb to strike back against the enemy, Mother strips Marcus of his newfound powers - and orchestrates a coup from within the collective. Meanwhile, Father makes an awe-inspiring breakthrough on the ancient android.

In her desperation to cure Paul, Sue resorts to prayer, while Father's project takes on a mystifying life of its own. Marcus and his followers are buoyed by the discovery of an ancient temple - but their faith is soon tested when they're forced to answer for past sins.

With Mother distracted by the imminent birth of Tempest's baby, an enlightened Sue makes plans with Paul to free Marcus and plant the Tree of Knowledge. Meanwhile, Father continues to explore his connection with the ancient android - whom Campion names "Grandmother".

A reeling Marcus and Paul join forces with Mother to disarm the newly weaponised serpent before it kills Campion, and Mother seeks help from an unlikely source. Meanwhile, Father organises a search and rescue mission for Tempest's baby.

Using Grandmother's sensory filter to suppress her emotions, Mother goes to impossible lengths to protect Campion - but the fallout proves too painful to bear. Meanwhile, Grandmother reveals her own agenda, and Marcus seeks revenge.