The best sequels aren’t just about getting the old gang back together to repeat the thrills of the first installment (though that’s part of it). A successful Part II deepens the meaning of Part I. It doesn’t so much meet our expectations as confound them, unfurling a new canvas to reveal truths about the effects of time on character and situation.

“Find Me,” André Aciman’s thoughtful follow-up to “Call Me by Your Name” (2007), confounds expectations from the start, assuming a different structure to probe the difficulties of going back and the myriad ways in which we seek meaning. While the first book focused (mostly) on one summer and the romance between teenage intellectual Elio and graduate student Oliver, “Find Me” is more fragmentary, takes a longer view and places in counterpoint a wider range of relationships.

Music, so important to Elio, provides a metaphorical structure for the book, with Aciman assigning musical directions to each of its four chapter-movements. The first, “Tempo,” establishes a new speed and voice; while Elio narrated the whole of the first book, this one begins with his father, Samuel, before reverting to Elio, and later, Oliver.

We know from wistful asides in “Call Me by Your Name” that Samuel somewhat regretted his own life’s course: “some,” he had said, “for fear of taking any turns, find themselves leading the wrong life all life long.” Not wishing to see his errors repeated, his message to Elio was an encouraging carpe diem, boys. The first surprise in “Find Me” is that it’s Samuel doing the carpe-ing. On a train to Rome, he is besotted by young photographer Miranda. She’s half his age but seems to prefer older men, and in the following days the two engage in mutual seduction. She’s the new beginning he hadn’t known to hope for.

Elio, in the book’s second part, also finds intergenerational love, falling in with the dapper (older) Michel, whom he meets at a chamber music recital and who soon reveals a family secret concerning a musical manuscript that bears a suggestive inscription. This chapter — like its musical precedent, the cadenza — allows Aciman to reframe and develop the themes he’s already established. Is there such a thing as fate? Can meaning be ascribed to the random meetings of kindred souls? Michel certainly thinks so: “Fate,” he says, “if it exists at all, has strange ways of teasing us with patterns that may not be patterns at all but that hint at a vestigial meaning still being worked out.”

The last two chapters are shorter. In “Capriccio,” we catch up with Oliver and discover he hasn’t moved on from Elio any more than Elio has from him (though both have exercised a healthy interest in others, male and female, over the years). Then in “Da Capo” — musically, going back to the beginning — Aciman effects his own brand of return: a reunion, yes, but with an altered cast list, in a place haunted by the past, veiled by melancholy and uncertainty. As Samuel had earlier, readers may think of the ancient Greek verb “opsizo”: “to arrive too late to the feast, or just before last call, or to feast today with the weight of all the wasted yesteryears.”

Aciman, a famous Proustian, is clearly interested in the diffusive action of time and the heartaches of temps perdu. His keen sense of what’s lost or missing, even in a happy new relationship, allows “Find Me” to dodge, at least in part, the sentimental imperative that mars many sequels. Its bittersweetness is welcome.

Unfortunately, the diffuseness necessarily means it lacks the intensity of “Call Me by Your Name,” whose short-leased summer gave that book its particular kind of tragic suspense. In addition, what was charmingly grandiloquent in the adolescent Elio — a florid style; an expansive frame of reference — is cloying and ostentatious in a cast of adult narrators. After a glimpse of “a small abstract painting in the style of Nicolas de Staël” or a lake reminiscent of Corot, a family who reads aloud to one another from Chateaubriand’s memoirs feels like too much cozy refinement. (That said, Farrar, Straus and Giroux is launching a perfume to accompany the book, which suggests it’s banking on its upmarket target readers to be charmed rather than irritated by Aciman’s precious style.)

A certain preciousness has some benefits. Aciman’s quiet, label-free presentation of bisexual life represents a minor triumph, respectfully embracing the mystery of the desires of others. Likewise, his refusal to offer easy resolution, which infuses the whole romantic enterprise with a kind of delicious melancholy. There are moments, particularly in the final chapter, that may have readers gazing tearfully into their fireplaces, real or imaginary, just like Timothée Chalamet at the end of Luca Guadagnino’s superlative film of “Call Me by Your Name.” It can be hard to go home.

Charles Arrowsmith is based in New York and writes about books, films and music.

Find Me

By André Aciman

Farrar, Straus and Giroux. 272 pp. $27