Kathy H., a thirty-one-year-old carer, introduces herself and begins narrating memories of Hailsham from the vantage point of someone who already knows how the story ends.

Kathy describes Hailsham — the Sales, the Exchanges, the guardians — and recalls Tommy's public humiliation and inexplicable rages, which she alone tries to understand.

Miss Lucy tells the children more directly than any guardian has before what they are and what will happen to them. The school's vagueness is deliberately cultivated.

The mysterious woman called Madame regularly visits Hailsham to select the best student artworks for a 'Gallery.' Ruth spreads rumors about what the Gallery means.

Ruth maneuvers Tommy into becoming her boyfriend, Kathy notices but suppresses her own feelings, and the relational triangle that will govern the next decade quietly solidifies.

Kathy searches for a replacement for her lost 'Songs After Dark' tape and finds Tommy watching her dance alone in the dormitory — a moment of pure accidental intimacy.

The guardians' sex education takes a peculiar form, and Kathy discovers Miss Lucy smoking alone in a room — an image of adult despair the children cannot yet interpret.

Kathy and the others speculate about what lies beyond Hailsham's grounds, and Ruth disciplines Kathy with social exclusion after Kathy violates an unspoken rule.

Kathy, Ruth, and Tommy leave Hailsham and move to the Cottages — a run-down farmhouse where older clones prepare loosely for their futures. The world outside Hailsham is encountered for the first time.

Ruth becomes obsessed with finding her 'possible' — the human original she was cloned from. Kathy notices Tommy and Ruth drifting apart while Tommy shares his theories about the Gallery with Kathy.

Ruth, sensing Tommy and Kathy's closeness, delivers a calculated speech telling them the deferral is a myth and that carers and donors like them never end up together.

The group drives to Norfolk to find Ruth's possible. The search fails. Kathy finds a replacement for her lost tape, and the trip ends with a sense of irreversible drift.

The narrative jumps forward. Kathy is now a carer. She describes the work — visiting donors, helping them through their donations, watching them 'complete.' She has been doing this for almost twelve years.

Kathy reconnects with Ruth, who has begun donating. Ruth is diminished, quieter, something has gone from her. Kathy becomes her carer.

Ruth, Kathy, and Tommy make a trip to see a boat Ruth has always wanted to visit. Ruth apologizes — for the decade of separation, for the cruelty — and gives them Madame's address.

Ruth dies after her fourth donation. Kathy is her carer until the end. The loss is recorded in the same flat, careful language Kathy has used for everything.

After Ruth's death, Tommy and Kathy become a couple. The relationship that was delayed for a decade finally begins — too late, too close to the end.

Kathy and Tommy use Ruth's address to track down Madame and request a deferral. They are received at Madame's house and meet Miss Emily again.

Miss Emily explains what Hailsham was: a campaign to prove clones could be educated and feel. The Gallery read souls not to grant deferrals but to demonstrate humanity. The deferral was never real.

Driving away from Madame's house, Tommy asks Kathy to stop the car and walks into a field and screams — the last, most adult expression of the rage that has lived in him since Hailsham.

Tommy completes after his third and fourth donations. Kathy cares for him until he is gone. The relationship ends in the same quiet, careful language everything else does.

After Tommy's death, Kathy drives to a field in Norfolk and stands in the wind. She allows herself one moment of imagining he is there. Then she gets in the car and drives back.

Kathy has received notification that she will become a donor. She reflects on everything she remembers and prepares, in the novel's final pages, for what comes next.