Paul Tough’s important new book on the broken promises of higher education begins with a chapter that he succeeds in making as suspenseful as the prologue of any serial-killer novel and as heart-rending as the climax of an epic romance. It describes a high school senior who is waiting to hear if she has been accepted at Princeton and the University of Pennsylvania.

Her name is Shannen. She’s from a poor family in the Bronx. She has worried so much and worked so hard that she’s underweight and permanently exhausted. And she believes — based on all the conversations around her, all the cultural cues — that her entire future hinges on the answers from these institutions. Her worth as a person hangs in the balance. The thought of college doesn’t flood her with excitement. It reduces her to a sobbing wreck.

I won’t tell you where she ends up, because that’s a spoiler. It’s also not the point of her story or of “The Years That Matter Most: How College Makes or Breaks Us,” which will be published next week. Shannen exemplifies how college — once a bright beacon of promise and potent engine of advancement — has turned into something that’s often dysfunctional and downright cruel.

At its best, it remains a ladder to higher earnings, greater economic security and dreams fulfilled. For some lucky students, it’s still an exhilarating and enormously fun rite of passage. And America’s standout schools inspire envy around the world.

But for too many students, college is a letdown, betrayal or taunt. And Tough — whose previous book, “How Children Succeed,” was an influential bestseller — explores the various reasons and the toll on young adults at every socioeconomic level, though it’s poor and middle-class strivers who are the most badly served by far.

In an increasingly pessimistic country with fewer manufacturing jobs than decades ago and a widening chasm between the haves and have-nots, college looms enormous in young people’s psyches. But the mechanics of getting to and through it are messier than ever. As Tough writes: “A generation ago, earning a four-year college degree was rightly seen as a way for individuals to move up in the world. Today, for many young Americans, a BA is simply an insurance policy against moving down.

That dark fact has changed the way many of us think about college,” he continues. “It means that when young people make their decisions today about college, they often are motivated less by hope and more by fear.”

He introduces student after student whose route to college and experience there are rocky in the extreme. There’s Shannen, tortured by how much social, cultural and financial importance is attached to a school whose acceptance rate is no higher than 10% and whose yardsticks for applicants favor those from backgrounds exponentially more privileged than hers.

There’s Clara, who should be joyful — she has no financial worries and many excellent college options — but is bullied by her parents to bypass Middlebury, which she prefers, for Yale, which is yet more exclusive. Hers isn’t a sob story, I know. But it’s a dispiriting confirmation of the bragging rights and brand obsession that pervert higher education today.

Along with Shannen’s distress, it may also help explain why more and more college students report and seek help for mental health issues. According to the American College Health Association, the percentage of students who profess a degree of anxiety that affects their studies has risen to 27.8 from 18.5 a decade earlier. The percentage who say that about depression has risen to 20.2 from 11.6.

In rural North Carolina, Tough meets and interviews Kim, whose working-class family doesn’t do much to encourage her ambition. She gets into Clemson all on her own. Then she can’t go, not right away, because the math of paying for it just doesn’t work. Her optimism collides with — and is put seriously to the test by — the punishingly high cost of college in a country where, according to the Federal Reserve, there are more than 44 million borrowers who owe $1.6 trillion in student loan debt.

KiKi nets the scholarships and financial aid she needs for Princeton. But she finds herself in such a tiny minority of poor students there that she feels culturally adrift. She’s routinely reminded of and stressed by the social and economic divisions between her and other students. Tough’s reporting makes clear how painfully common this experience is, because despite the most elite schools’ pledges and boasts about diversifying their campuses, they’re still theaters of extraordinary affluence, with screening practices that keep them that way.

All in all the landscape of higher education in America is forbidding to students of limited means. Many of them enter college academically behind their wealthier peers, who got better K-through-12 educations, and schools do too little to help them catch up. Many are lured to for-profit institutions that rake in money while failing to deliver on their promises.

And that has dire consequences not just individually but also nationally. To spur innovation, compete globally and nurture prosperity in a country where factory jobs have ceased to be the answer, we need more, better college graduates. So why aren’t we doing more to create them?

Near the end of his book, Tough recalls the high school movement of the early 20th century, when industrialization called for a more skilled work force and America responded by making sure more of its citizens finished high school. Only 9% of them did in 1910. By 1940, that figure was up to 50%.

In the current era of technology and automation, college is the new high school, but the share of Americans finishing it hasn’t grown at nearly that kind of pace. According to the Census Bureau, about 35% of Americans 25 years or older have earned four-year college degrees or more, in comparison with about 21% 30 years ago.

“We’re not responding in the same way,” Tough told me. Instead, he said, the attitude is more along the lines of “you figure it out, you pay for it, and we’re going to make it as hard as possible.”

That needn’t be so. Among his book’s many vital contributions are its portraits of schools and programs that model a better way. He finds hope, for example, at the University of Texas at Austin, where admissions have been rethought, extra guidance has been provided and a few professors in particular have decided to go back to the beginning, more or less, and pour extra energy into actual teaching. For them and their students, college isn’t just a badge that you do or don’t get to display. It’s something infinitely more transformative. It’s an education.

Frank Bruni is an Op-Ed columnist for The New York Times.