Kristen Sewart and Dakota Fanning enter a studio in preparation for their upcoming film “The Runaways.”

Next week, Kristen Stewart and Dakota Fanning start rocking out on a biopic about four teenage punk pioneers. Now, we’ve got the scoop on the final female who’ll help get the band back together.

“We just closed everything,” Alessandra Torresani revealed to us Sunday. “It’s really exciting.”

The 22-year-old Torresani — a former child star who has more than 20 TV and film credits in the last decade — is the final member to join “The Runaways,” a high-profile biopic about the “Cherry Bomb” band. With Stewart set to play Joan Jett, Fanning onboard as Cherie Curry and Stella Maeve cast as Sandy West, Torresani will play one of the band’s most notable alumni.

“I’m playing Lita Ford,” Torresani said of the heavy-metal icon behind such hits as “Kiss Me Deadly” and “Close My Eyes Forever.” “She’s the most incredible woman. I’m getting to meet her very soon, so that’ll be amazing. I’ll get to hear all her old stories.

“There’s some kick-ass girls in the movie, right? It’s going to be great,” laughed Torresani, who we caught up with at Hollywood Life’s Young Hollywood Awards. “We’ve got some good girls in there.”

The Runaways were a particularly dynamic band during their brief 1975-79 run because Jett and Ford (who joined the band when she was 17) were formidable guitarists. Now, Torresani laughed, she has less than seven days to learn how to convincingly wield her axe.

“I learn the guitar starting [Monday], so that’ll be interesting,” she laughed. “I’m very nervous about it.”

Torresani told us she’ll be picking up the guitar as she meets Stewart, Fanning and Maeve for the first time and that the newly formed band has less than a week to rehearse. “I haven’t met any of the girls yet. I’ll meet them soon. I see them tomorrow, so that’s soon enough,” she grinned. “I can fake [the guitar]. I can rock out. I’m a dancer, so I’ll fake it.”

A professed “Twilight” fan, Torresani also told us that she’s eager to meet “New Moon” stars Stewart and Fanning. “I love ‘Twilight.’ Who can’t love vampires, right?” she grinned. “And Robert [Pattinson], of course. Gorgeous!”

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