There's no beating around the bush in The Wanting Seed. The novel gets off to a grim start as Beatrice-Joanna Foxe watches the dead body of her infant son get packed off to the Ministry of Agriculture, where it'll be turned into fertilizer. As Beatrice-Joanna struggles to manage her grief, the State Health Service staff shuffle her out as quickly as they can. In a world where human beings outweigh the global food supply, no "modern" person (1.1.9) cries over one less mouth to feed.
As Beatrice-Joanna leaves the State Health Service, she treats the gay and lesbian staff with "instinctive" (1.1.11) loathing and prejudice. Everywhere she looks, London, England is full of propaganda encouraging homosexuality. Same-sex relations may help to keep the population down, but to her, they seem unnatural and "unclean" (1.1.13).
As Beatrice-Joanna heads from the State Health Service to the Ministry of Infertility, her husband, Tristram Foxe, starts the day's shift at the boy's school where he teaches modern history. A senior colleague of his has recently died, and Tristram is sure he'll be promoted in his place.
After filing her son's death certificate at the Ministry of Infertility, Beatrice-Joanna makes a date with Tristram's brother Derek Foxe, a high-ranking Ministry official with whom she's been having an affair. Meanwhile, back at the boy's school, Tristram learns that he won't be getting that promotion after all. As it turns out, not being gay is a serious liability.
In Beatrice-Joanna and Tristram's apartment, Beatrice-Joanna and Derek sleep together, and Beatrice-Joanna "forgets" to use birth control. Tristram leaves work early and heads to a pub, where he gets drunk and witnesses an act of police brutality. By the time he gets home, the world looks pretty awful from his point of view.
Beatrice-Joanna feels instinctively that she's now pregnant with Derek's child, and so, just to be on the safe side, she sleeps with Tristram too.
It's been quite a day for both of them!
In the months that follow, Beatrice-Joanna's pregnancy is confirmed. Tristram believes the child is his, and insists that Beatrice-Joanna induce a miscarriage. He's terrified because the government is cracking down on men and women who don't abide by the strict population laws, and life in the city is getting very dangerous for families.
Captain Loosley, one of Derek's rivals at the Ministry of Infertility, snitches to Tristram about Derek and Beatrice-Joanna's affair. Tristram is furious. He confronts Beatrice-Joanna in the street outside their apartment building, but before they can really have it out, Tristram gets swept up in a labor protest that's marching through the street. While Beatrice-Joanna slips inside, Tristram is caught in the violence that breaks out when the police attack the protestors, and he's soon carted off to jail.
Beatrice-Joanna flees to her sister and brother-in-law's farm in Northern Province, intending to wait out her illegal pregnancy there. Meanwhile, Tristram is stuck in prison, and Derek makes sure he'll be there for a long time.
Seven months later, Beatrice-Joanna gives birth to twin boys whom she names Derek and Tristram. As Tristram escapes from prison with the help of an altruistic cellmate, Beatrice-Joanna and the twins are captured by Captain Loosley and the Population Police, who hope to discredit Derek by exposing his heterosexuality and paternity.
Tristram makes his way north, hoping to reunite with Beatrice-Joanna. At the same time, Beatrice-Joanna and the twins are moving south with Captain Loosley and the Population Police. As Tristram moves through England's rural villages, he realizes that cannibalism and ritualistic (heterosexual) fertility rites have become the new norm. Priests are preaching the doctrine that "all life is one," and villagers are trying to counteract the crop blight by sowing a little "seed" of their own.
Tristram finally makes it to Beatrice-Joanna's relatives, only to discover that she and the twins are long gone. As he starts to make his way back towards London, he's tricked into joining the British Army.
Tristram spends several months as a Sergeant-Instructor in the army, giving the troops basic training in reading, writing, and arithmetic. When his superior officers learn that he's also trying to teach the soldiers critical thinking, he's transferred to a rifle company, and shipped out for action. None of this makes any sense to Tristram, as war has been outlawed on Earth for generations.
Tristram and his company are shipped into unknown territory, and told that they'll be marching to the front soon. One of the other officers recognizes the air and the landscape, and tells Tristram he's sure they're on the west coast of Ireland.
Tristram is sure that this "war" is all just a pretense, and that he and the other soldiers are going to be killed off by their own people somehow. He and his company march to the trenches, and when the battle begins, Tristram is horrified to see that the "enemy" is a battalion of English women.
Tristram survives the massacre and manages to make his way back to England. After his one-year contract with the British Army expires, Tristram heads to the London War Office to be discharged, and swears that he'll expose what the army is doing. The Major who discharges him isn't too concerned: after all, they're all just following orders from the Global Population Limitation Authority.
Equipped with his discharge papers and his back-pay, Tristram heads back to Brighton. He finds himself a new teaching job and a new apartment, then goes to look for Beatrice-Joanna at the seashore, where he knows she walks with the twins each afternoon.
Beatrice-Joanna and Tristram reunite, and they live happily ever after in a world where human fecundity is celebrated, the surplus population is shipped off to fake wars called "Extermination Sessions," and the dead corpses are sold to capitalists running cannibalistic meat-canning factories. And they all lived happily ever—er, wait—just kidding. It's a pretty bleak ending to pretty bleak story.