When Jonathan Franzen published "The Corrections" in 2001, he became at once a major author and a target for gripes about major authors. For many fans he's among the last of the true believers in the social novel, committed to hefty fiction that's awake to political and cultural forces. To detractors, Franzen's Olympian posture is outdated, privileged and presumptuous get-off-my-lawn-ery. Franzen sells well, but culturally he runs counter to a reigning individualistic perspective: If Twitter didn't have him for a punching bag, it would've had to invent him.

Excepting one character's complaint about a "plague of literary Jonathans," Franzen is unconcerned with all that extracurricular noise in "Purity," a novel that doubles down on the social commentary but has the wit and intricacy of his best work. Its heroine, Purity (aka Pip), is introduced as an everymillennial saddled with personal concerns: college debt, a dead-end nonprofit job, a controlling mother who withholds information about her father. But when Pip heads to Bolivia to intern for Andreas Wolf, the charismatic head of a WikiLeaks-style muckraking group, her world rapidly complicates.

"Why does a man with bad morals pay a beautiful young woman to come to South America?" Pip's mother asks. Much of "Purity" turns on that question, and on those bad morals, too. Andreas is sociopathically manipulative and persuasive, a serial seducer of troubled teens while growing up in East Germany. He's also, we learn early, a murderer with a Russian novel's worth of rationalizations and torments.

If Franzen had stuck with this binary conflict — "wolf" vs. "purity" — the novel might rightly earn his critics' pre-emptive strikes. But "Purity" is thoughtfully concerned with the nature of control in various forms — men over women, governments over data, morality over behavior — and Franzen expertly connects the plot's multiple vectors.

Through Tom, a journalist, Franzen explores the way money frays emotions; through Charles, a despairing novelist, he plumbs the difficulties of marriage and limitations of art. Others' actions wind up weighing heavily on Pip, and the novel's central concern is how much of our previous generation's baggage we're doomed to lug around.

In his prior novel, "Freedom," Franzen delivered smug responses to similar ethical quandaries: Its prose was a finger in the chest of every American with an NPR car preset. He's not immune to grand statements in "Purity": "The world was overpopulated with talkers and underpopulated by listeners," for instance.

But he's much more comfortable with ambiguity. Pip is a naïve and idealistic hero, but her coming of age is unshackled from certainties and reassurances, and more alert to complication. We're all sullied, Franzen insists, and you may not need Franzen to tell you that. But he's better than most at revealing what sullies us.

Mark Athitakis is a reviewer in Phoenix.