Like nearly every Houellebecq novel, “Serotonin” should be stamped on its spine with a tiny skull and crossbones, like you used to see on bottles of poison, to keep away the devout, the unsuspecting and the pure of heart. His fiction picks up topics like prostitution, sexism, pedophilia, pornography, racism, torture and sex tourism as if they were cans of diet soda. He turns them over to observe them coolly, neutrally and often comically from all sides. He triggers intense responses.

It’s strange that the word “morality” keeps coming up when one is talking about this laureate of decadent ennui. (People who read Houellebecq really like talking about Houellebecq.) The historian and essayist Tony Judt once declared that “moral seriousness in public life is like pornography; hard to define but you know it when you see it.”

When you begin to read a Houellebecq novel, you intuit his moral seriousness. It may not be your morality. There is the consistent sense that this nihilistic writer is drawing from a deep well; his voice is uniquely present on the page. He’s well-read, conversant with politics, philosophy and economics. He wears his learning lightly. Like the Devil in “Paradise Lost,” he gets, in this wary literary climate, all the good lines. Few can be printed here.

Houellebecq’s last novel, “Submission” (2015), arrived in France like gasoline drizzled over a lit match. It depicted an Islamist takeover of France’s institutions, and it was published on the day of the Charlie Hebdo shootings, when Muslim extremists slaughtered the staff of a satirical magazine that had lampooned their religion.

That novel started intense debates, and a copy of the book was useful to have in these arguments. You could toss it at your adversary and impede their progress for a moment or two, and thus make your escape.