"I come prepared," says Emmy Rossum, grasping a roll of quarters with both hands, like the hilt of a sword. She's leaning against a railing on the Santa Monica pier in oversize sunglasses and tight jeans, wearing the kind of half-cocked grin that says "You're goin' down." She leads me across the planks into the Playland Arcade to search for the form my demise will take.

Rossum, 22, is fresh from Mexico, where she spent four months filming the manga-inspired Dragonball Evolution, in which she plays Bulma, the film's weapons-obsessed inventor/scientist/all-around ass-kicking heroine. That's four months of bo-staff sparring, stunt riding, knife throwing, and martial-arts combat. As we comb the dark aisles for a slot to feed, I come to this painful realization: Whatever we choose, I am pretty much screwed.

"I just learned how to ride these, and it was so much fun!" she says, tapping the seat of a motorcycle game. "In an underground abandoned parking lot—without a license. Don't tell the cops!" At the broken-down Wild West target range, she pats the butt of an air rifle like she's been shootin' food for decades. "We trained with real ones down in Mexico," she says. "They give your shoulder a real kick!" Over the techno din of Dance Dance Revolution, I make a plea for my dignity. The prospect of going toe to toe—virtually or not—with a girl who trained with the same kung fu master who taught Chow Yun-Goddamn-Fat strikes me as, well, hopeless. So instead we crawl inside a mock safari jeep and spend 40 bucks' worth of quarters blowing the holy hell out of giant arachnids in a two-person shoot-em-up called Let's Go Jungle. Whoever happened to wander by during those 45 minutes was treated to the sweetest, most melodic voice ever to utter the words "DIE, YOU BASTARD!!!!!"

Those dulcet tones are part of the Emmy Rossum mystique. Ever since she sang to us, at 13, as the honey-voiced Deladis Slocumb in 2000's Songcatcher, she's been that little girl with the golden pipes. Born and raised in New York City, Rossum was the only child of a tough, independent single mom (Rossum's never met her dad, who left her mom while she was pregnant). She barely managed half a semester at Columbia University before success assaulted her.

"I was in the middle of a French final," she says, "and I got a text message from my agent telling me I got Mystic River and The Day After Tomorrow—on the same day!" Then, while still 18, she beat out Anne Hathaway and Keira Knightley for the lead in the film Phantom of the Opera. Despite being nominated for a Golden Globe for that performance, Rossum took a yearlong break from acting to record a CD of original pop music called Inside Out. Yes, yes, she's well aware of our collective eye-rolling at the tired I-am-celebrity-hear-me-sing gimmick—which is why she'd much rather inspire comparisons to Judy Garland or Bette Midler than to a certain hotel heiress. Rossum's been singing professionally since age 7, when she joined the children's chorus at the Metropolitan Opera—a gig that paid her five bucks an outing. "There was a horse onstage making $150," she says.