Alice Adams’s moving debut begins with an ending.

It’s 1995, in Bristol, England. Friends Eva, Sylvie, Lucien and Benedict lie entwined on a grassy hilltop, drinking from a bottle of wine, soon to leave the idyll of university. Life’s possibilities span before them like the city below. With affectionate languor, Eva asks, “If you could know the answer to any question, what would it be?”

"Invincible Summer" by Alice Adams (Little, Brown)

On reading this bittersweet and compassionate novel, which sweeps this group in and out of each other’s lives from their 20th to their 40th year, I had a few: Are we agents of our destiny or flotsam bobbing on the tides of chance? Does aging make us wiser, or just old? How do we reconcile our wrongdoings, if we never witness their harm? Is settling the path to happiness, or kind of a bummer? What did Camus mean when he wrote, “In the depths of winter, I finally learned that there lay within me an invincible summer”?

Upon graduation, this quartet tumbles helter-skelter into adulthood. Adams casts a keen eye on that slow shock of the 20s, when even the most exceptional young people discover they are just . . . people, with jobs and partners decided as much by happenstance as by desire.

Eva, who calls herself “Eva Nobody from Sussex,” notes the prosperous gleam of the Morton Brothers investment bankers at a recruitment fair and joins their program to become a derivatives trader.

Siblings Sylvie and Lucien set off hosteling through India. Sylvie’s talent as a painter blazes as bright as her flaming orange hair; all assume her travels are but a brief deferral of stardom. Lucien is a “sardonic, bullet-proof” club promoter with a shady sideline, a charmer whose number best be deleted by dawn — unless you’re Eva. She’s pined for him for years.

It’s only sweet, reserved Benedict, an affable update of Mr. Darcy, who knows what he wants: to become a particle physicist and to be with Eva. After a summer at home, he’ll return to Bristol to study for his PhD.

But what a home! Benedict gathers his meager courage to invite Eva to his family’s terraced Corfu manse above the “glittering Ionian Sea.” There, Eva discovers that unlike her gray puddle of a childhood, the rich life is a “marvelous secret . . . like being suspended in a thousand shades of blue.” As hot as she is on the loot, she’s cool on Benedict, and in no mood, at 22 , for a long-distance affair.

The friends’ fates rise and fall. There are career highs and implosions, marriage and infidelity, addiction, prison — and funny, biting insights on how relationships can detonate when one friend has children and another does not.

The book’s structure — reminiscent of David Nichols’s “One Day” — skips from (mostly) summer to summer, returning to characters only when they return to each other. An intricate pattern of how deeply they influence each other emerges.

The author Alice Adams (Little, Brown)

Like your favorite Austen novel, “Invincible Summer” reconciles the cultural reality of an era with the personal lives of its characters. But Eva is not as reflective as, say, Elizabeth Bennet. When she knowingly makes the kind of bad trades that precipitated the financial crisis of 2008, she is bothered only by their effect on her career, as if busting a glass ceiling absolves her of busting the economy.

Rather, it’s in Sylvie’s hard fall that the beauty and depth of the book resides. It’s she who reads Camus, and discovers, “at last, that in the worst years of our madness, the memory of that sky had never left me.” The hopes she thought she’d lost were always with her, invincible. So what if Camus is referencing the ravages of war, and she the mess of her 20s? It holds.

That grassy Bristol hilltop is the first of many. At seminal moments, look up! Eva stands at the top of a rise, civilization below. Her perch mimics the novel’s bird’s-eye vantage, but also Eva’s drive, for better and worse, to vault above the fray. As she evolves, she moves downward, first with a business idea that puts Eva and Sylvie’s combined ingenuity at every Londoner’s front door, and later, with her friends, all so changed, to the ocean’s edge: an elemental, eye-level vastness belonging to no one, as graceful a symbol of their passage to maturity as any.

Sophie McManus is the author of “The Unfortunates.”

Michael Dirda is on vacation.

Invincible Summer

By Alice Adams

Little, Brown. 308 pp. $26