Emily St. John Mandel doesn’t seem like the paranoid type. Cheerful and preternaturally poised, she spends her free time tending to the flower beds in her rooftop garden in Brooklyn and working on her rudimentary French.

But last fall, she started fretting about the end of civilization — specifically, whether publishers were growing tired of the dystopian trope. She was shopping around her new novel, “Station Eleven,” which is set in the near future, after a flu pandemic has wiped out most of humanity. Ms. Mandel, who got her start writing crime fiction, worried that the post-apocalyptic wave had peaked.

“When I started writing, there were a few literary post-apocalyptic novels, but not quite the incredible glut that there is now,” Ms. Mandel said in an interview on her terrace. “I was afraid the market might be saturated.”

It wasn’t. A three-day bidding war broke out among a half-dozen publishers. The novel sold to Alfred A. Knopf, which paid a mid-six-figure advance, far more than Ms. Mandel had made on her previous three novels combined. She now feels reassured — if not about the future of the planet, then at least about the shelf life of dystopian fiction.