By Anthony Breznican, USA TODAY
Kristen Stewart's two new Sundance films are not for kids.
Come to think of it, maybe they're not for parents, either.

These twin tales of young girls led astray by abuse, sex and drugs are enough to make devoted moms or dads run home to hug their daughters — and maybe pre-emptively ground them for life.

Stewart's Sundance performances are a nervy step forward for the 19-year-old actress, reminding moviegoers that her talents expand beyond the vampire/werewolf love triangles in Twilight and New Moon that made her a movie star.

In Welcome to the Rileys, Stewart is a 16-year-old stripper/prostitute who lives alone in an abandoned house and seems bent on self-destruction. Two grieving parents (James Gandolfini and Melissa Leo) decide to save her, driven by the memory of a daughter they couldn't save.

The Runaways is a more fun-loving story set in the 1970s music scene, but it's no less harrowing.

Stewart plays future rock goddess Joan Jett, and Dakota Fanning is singer Cherie Currie, founding members of the all-girl punk band of the title, who rise spectacularly and collapse the same way, lucky to escape with their lives from drug-fueled excesses and an abusive manager eager to cash in on their nascent sex appeal and vulnerability.

At an after-screening Q&A for Rileys, Stewart said she was drawn to these exploited girls because they are so different from herself. "I've not had problems. I've never experienced anything that bad. Nobody has ever taken anything from me. I've always had all the choices and options or whatever."

One thing she did share: the character's defensiveness. "I knew exactly what it felt like to be sort of protecting something," she said.

Visibly shaking with stage fright, Stewart tended not to say much in front of the crowds. But after the Runaways screening, she said Jett and Currie's struggles were more than just shocking and scandalous — they cleared a path for her generation.

"We've grown up being told that, as girls, we can do whatever we want," Stewart said. "And that just wasn't the case for them."