THE FIRST THING you should know about Kristen Stewart, at least according to her three-time costar Jesse Eisenberg, is that she has an infallible phoniness meter: “Kristen is naturally suspicious of pretense,” Eisenberg says. “She calls it out in herself, in a story, in others. We were filming an emotional scene at the end of Adventureland, when Kristen was just 17 years old, and she called ‘cut’ in the middle—on herself. She said, ‘I’m lying! It’s not feeling fully authentic!’ She has the most unusual lack of vanity in an industry that doesn’t seem to promote that. I use her as my rubric to figure out what I should trust.”

Stewart is, above all things, an honest actress, which is what makes her so beguiling to watch. She never forces emotion or attempts to dominate a scene, yet she can hold an audience’s attention with nothing more than a sideways glance. There are few actors who can seem so completely natural inside a performance, but the fact that Stewart has been able to laser in on truthful expression at such a young age—she’s still only 26!—has made her a singular kind of movie star.