Describing her Brooklyn writer's shack for T: The New York Times Style Magazine, novelist Emma Cline called a drawing of Tom Cruise that hangs on her wall “a tawdry subject executed with a lot of sincerity.” Whether she winked when she wrote it, this reviewer does not know, but the words could just as easily describe Cline's fiction debut, “The Girls,” a coming-of-age novel in which a 14-year-old California girl spends a summer in the orbit of a Manson-like cult. The novel made news when it sold at auction in a three-book, seven-figure deal, proving that tawdriness and sincerity are a winning combination.

If the subject matter is delightfully sleazy, the treatment is high M.F.A., written in dreamy, lyrical flashbacks from the point of view of an older, wiser Evie remembering the summer of 1969. Young Evie, neglected by her newly divorced mother and isolated after a fight with her best friend, becomes enchanted from afar with Suzanne, a bohemian sylph who haunts the Haight. Soon, Evie is climbing into a school bus headed for a dilapidated ranch in Marin County, where she meets Russell, the charismatic, middle-aged leader of a teen girl harem. “There was so much, that first night, that should have been a warning,” present-day Evie intones.

Cline's lyricism relies on sentence fragments and poetically fudged parts of speech (“the gauzy light that made their skin illuminate and pale” begs the question of whether the skin is being illuminated or illuminating something else). The passages from Evie's pre-Suzanne life are particularly satisfying; relieved of the burden of sensationalism, the prose dances through ordinary beats of adolescence with an awkward grace.

Many of these details revolve around Evie's budding sexuality, about which Cline is never precious. Evie masturbates furiously and pansexually, equally aroused by the illustrations in children's books and the naked women in her father's porn collection. Even her crush on her friend Connie's older brother is queasily augmented by her sexual ignorance: “Peter never wore underwear, Connie had complained, and the fact grew in my mind, making me nauseous in a not unpleasant way.” By contrast, actual encounters with boys and men leave Evie numb, passive and disembodied: “I would be shunted along whatever would happen, I understood. However he piloted the night. And there wasn't fear, just a feeling adjacent to excitement, a viewing from the wings. What would happen to Evie?”

What, indeed? Unfortunately, never quite as much as you want to happen to her. Evie hangs out at the ranch with Russell's malnourished groupies, lies to her mother and steals money from her purse, takes whatever drugs she is given and participates in sexual debauches. But she never goes feral, and neither does “The Girls.”

That's partly because we know from the first chapter that Evie will not be a participant in the ghoulish climax modeled after the Tate murders. Evie's flashbacks are prompted by the arrival of a couple of lewd teenage boys and a fragile underage girl named Sasha, who reminds Evie of herself; now middle-aged, Evie is almost as eager for the boys' approval as she was in the past and doesn't exert herself much on Sasha's behalf. Nothing changes, the book seems to say; girls are as lost today as back then.

Perhaps they are, though the Manson girls with their seedy glamour seem like a special case. Maybe the trouble is that the real-world Manson family was just too interesting. By contrast, the “girls” of the title remain disappointingly vague, their relationships incoherent. A few girls get distinguishing details — one has pigtails, one a child — but Cline's prose turns them into blurry images from stock '60s footage.

Despite this type of descriptive lassitude, the pages do turn. “The Girls” is a reliable poolside read, appropriate for lightly sun-dazed attention, and Cline will have plenty of chances to perfect her blend of tawdriness and sincerity in future books.

Amy Gentry is a freelancer.