Writing last week from the seventy-ninth Cannes Film Festival, I noted that some of the best movies to première here are often overlooked for prizes. The events of the past few days have forced me to amend that statement. During that time, “La Gradiva,” an exceptional début feature from the French director Marine Atlan, won the Grand Prix in Critics’ Week, an independently run program for first and second films that runs parallel to the official selection. Great things do, in fact, happen to great films, although Atlan’s movie was arguably still ill-served. I’ve heard more than one colleague suggest that it warranted a berth in the main competition, where it would have had a shot at winning the Palme d’Or, the festival’s highest honor.

Even without that distinction, it’s undoubtedly one of the year’s great discoveries. “La Gradiva” follows a group of unruly French high-school seniors on a five-day class trip to Naples and Pompeii, where the weather is warm and the scenery gorgeous enough to keep college-admissions anxieties at bay. It’s a travel saga, a coming-of-age drama, and a movie of precisely drawn, superbly individuated young characters who are nonetheless locked in myriad crises of identity, flailing about for a deeper understanding of who they are.

None is more bent on self-discovery than Toni (Colas Quignard), who comes at us in a charismatic blur of vulnerability and bluster. He boasts to his friends of his Italian roots—his mother, per family lore, is the love child of a lowly Neapolitan servant girl and her wealthy employer—but, having never visited Italy until now, seems less than confident in his new surroundings. Toni is goofy, disruptive, and behind on his schoolwork, a perpetual thorn in the side of his long-suffering Latin teacher, Madame Mercier (Antonia Buresi), who’s chaperoning the trip. At night, he cruises for men in the area, perhaps to dull the sting of his unrequited love for his smoother, more put-together best friend, James (Mitia Capellier-Audat). In the opening scene, set aboard a train bound for Naples, James hooks up with a girl in a compartment while Toni stands outside the door, a look of jealous longing on his face. Watching Toni from further down the corridor, and sharing in his loneliness, is Suzanne (Suzanne Gerin), a gifted student who deems herself too unattractive for romance and has made a bitter kind of peace with it. “Some girls have got to be unfuckable for others to be fuckable,” she says later, with sullen matter-of-factness.

Suzanne’s ungenerous view of herself is one of many misperceptions that will be overturned—some gently, some not. Atlan’s story hinges on bodies and minds in perpetual flux, and her filmmaking, rather than settling into the sun-dappled complacency of a travelogue, surges with life and a vigorous sense of possibility. A cinematographer before she turned to directing, she shot the picture herself, alongside Pierre Mazoyer, and, as that first sequence indicates, she has a talent for establishing relationships and layering tensions through the camera; a telling arrangement of glances is all she needs to lay out a clear, vivid emotional framework. But she and her co-writer, Anne Brouillet, also have a terrific way with words. Some of the film’s most captivating sequences are those in which Madame Mercier struggles to engage her students in discussion, and to suggest to them that there’s really no such thing as antiquity: the volatile impulses and volcanic passions that grip them are also the lifeblood of the ancient cultures and art works they’re studying.