The story line suggests a low-grade Saturday Night Fever: An improbably gorgeous girl works as a welder by day but is at her riveting best by night as she writhes and rolls for beer-guzzling millworkers in a Pittsburgh bar. But what Flashdance lacks in credibility it more than makes up for in the almost naked presence of newcomer Jennifer Beals, 19, whose body is the best reason for the film's astonishing $11.3 million haul at the box office in its first two weeks. Even critics who dumped on the film drooled over Jennifer. Her dancing, lauded the Los Angeles Times, "could melt steel plates off a battleship."

Beals, a bright, articulate Yale freshman, is hesitant about accepting the crown as a female Travolta. Shortly after Flashdance premiered last month, she raised a ruckus by admitting that much of her fancy footwork was done by a double, French dancer Marine Jahan, 24. "A lot of it is her," says Beals, an untrained talent who nonetheless worked on her dancing up to five hours daily for six weeks on location last fall in L.A. and Steel City. "I just did the best I could," adds Beals. "I'd do a shot, then they'd do Marine. It was up to the editor and director to pick and choose." Jahan, uncredited in the film (the producers call it an oversight), has seen Flashdance "several times," says her L.A. attorney, A. Lee Blackman. She believes that, except for the inserts of Beals' head and torso and a flip and spin in the last number (done by gymnasts), all the dancing was done by her. Beals feels she should set the record straight. "Marine even helped to teach me," she says.

Jennifer's bluntness extends to critics of the film's rather absurd story line. "Since when are films supposed to be real?" asks Beals, who has just completed an introduction-to-film-type course at Yale. "E.T. is not exactly a scientific documentary on extraterrestrials. The state of the art is illusion."

A teen model in her native Chicago, Beals is taking her own introduction to film in stride. "To an extent you are a commodity, and I got used to that [as a model]. It's not so bad. I get the feeling it's part of the nature of the business." But she balked at doing a nude love scene with Flashdance co-star Michael Nouri. "I said they could use a double," she explains. "My mother was happy about that," reports Jennifer. An intellectual Irish-Catholic, her mom was less pleased with one scene left in the R-rated film—Jennifer caressing Nouri's lap in a restaurant with her mesh-stockinged foot. "She thought that was sassy," adds Beals, "but as for the film, she can't help but love it."

Jennifer's father, Alfred Beals, a black owner of Chicago supermarkets, died when Jennifer was 9. She has two brothers—Gregory, 24, a writer in New York, and Bobby, 18, still in high school. Her mother, Jeanne, who teaches in a Chicago elementary school, married nephrologist Edward Cohen in 1981. "She really instilled a desire in me to learn for the fun of it," Jennifer says. "She made books like the Odyssey and the Aeneid seem like gossip columns."

While attending Chicago's Francis W. Parker School, Jennifer realized a way "I could make a lot more money for college than by baby-sitting and working at Baskin-Robbins": modeling. At 16, aided by top photographer Victor Skrebneski, she began posing for store catalogs and magazine fashion spreads. Her print work got her to New York and Paris during summers, though she adds, "I wasn't exactly traipsing into Vogue every day." Still, her modeling led to her audition for Flashdance, which she quickly filed away as a long shot.

Instead, she zeroed in on Yale—and was on campus just long enough last September to learn she'd won the part and to meet Bob Simonds, now 20. "We've been best friends and more since," she says. Filming Flashdance took four months, and now Beals has just wrapped spring semester. Her Yale chums don't include fellow actress Jodie Foster. (They shared a ride to New York once.)

Jennifer's time these days is spent mostly with sophomore Simonds. Riding in a limo from Yale to New York, they seem the perfect Hollywood couple of the future: the sultry starlet and the brash blond hotshot who'd like producer-director clout. On campus, they attend film society screenings—"everything," she says, "from artsy-fartsy to Spielberg"—and make Super 8 films with their film crowd cronies. Simonds found it "a huge hassle in the beginning" to be Mr. Jennifer Beals on campus. "I had this huge ego. I was used to people dying to meet me. Suddenly I was in her shadow or blocking her light. I'm desensitized to it now."

They'll have the summer to adjust. Jennifer says they may "traipse around Europe or go to L.A. All we know is we'll be together." Jennifer's fee for Flashdance will help pay for her four years at Yale—the first one set her back an "outrageous" $12,000 for tuition, room and board.

She hasn't picked a next script, though the offerings are piling up with her Chicago agent, Joan Ellis. Trusted amour Simonds admits he hopes there's not another Flashdance in the pile. "She was castrated. They cut out all her acting scenes." Still, the film has given Jennifer a focus for her sizzling looks and keen, intelligent energies. "I want to study and become a good actress," she claims. "I'm not in it for the glory."