The Children of Men by P. D. James
The year is 2021 and for the past 25 years, no children have been born. That last year's children are called the Omegas; they, like their elders, are sterile. The cause isn't quite certain but the results are devastating. Humanity faces its own mortality as a race. In England, they've fallen into a totalitarian regime led by the Warden of England and his council of advisors (four other people). The Warden's cousin, Theo Faron, is an Oxford professor who spends his time teaching courses on the Victorian era to adults who need a distraction. He himself needs distractions, especially from the memories of his dead daughter (whom he accidentally killed) and of his wife whom he never really loved. He's too clever for his own good, part of why he is such a damaged and isolated person. He, like the culture around him, wallows in self-pity and can't see a way out.
Then he mets Julian, a young-ish woman who is part of a group that wants to protest various atrocities that have sprung up since Omega year: (1) the Isle of Man is a prison colony with no order or direction--the inmates are running the asylum into the ground; (2) a death-with-dignity movement called Quietus has been coercing people to die early; (3) the Sojourners are immigrants from other countries who are effectively slave labor to the wealthy English economy and are treated like slaves; and so on. Julian's group wants Theo to approach the Warden with their demands for treating people, even foreigners and criminals, with dignity and respect. He knows they don't have a chance but he agrees to meet his cousin (who he hasn't seen in years) mostly because he's falling for Julian. Of course the Warden is uninterested in change but will Theo change in the process of helping Julian's group?
The book does an amazing job of both describing the world situation and developing the characters. The implications of a non-reproductive world have been thought out and presented believably. Countries jealously search for a medical answer to the problem and debate over how and if they would share a solution. State-sponsored pornography is readily available but people have lost interest in sex. Substitutes for offspring are baby dolls with varying degrees of realism. Also, people throw parties when a pet dog or cat gives birth. Even with a wealth of detail, the characters aren't lost in the world-building. Theo's journey from narcissism and depression is credible and captivating. The other characters, while secondary to him, are still well developed and interesting. The ending is surprisingly Christian in tone and content, which I found delightful and comforting.