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The big-name movie actor comes into the green room to promote his new venture into theatre. Instead of indulgently pontificating about the importance of the theatre he does something highly unusual — he engages in conversation.

The star in question, "The Social Network" actor Jesse Eisenberg, is known to be nervous and private. "The happiest moments for me creatively," he'll say later on, "are doing readings of a play around a table where there's no audience."

While the small talk does help put the self-effacing and fidgety Eisenberg more at ease, by the end of the interview it's obvious he's a thoughtful and engaged conversationalist.

Of course Eisenberg is also unlike those movie stars to whom theatre means Broadway star turns and Tony nominations. Eisenberg is appearing Off-Broadway, and is doing it in a play that he wrote — The Revisionist — at the Cherry Lane Theatre, and staged by Rattlestick Playwrights Theater. Starring Vanessa Redgrave, it is his second play for the company.

"He's a whiz kid who is really smart with a lot of talent," says Rattlestick founder David Van Asselt. "And he doesn't have a big ego."

Eisenberg, 29, started in kid's theatre in New Jersey and by 13 he was understudying on Broadway in Tennessee Williams' Summer and Smoke. Sure it was "nerve-wracking," he acknowledges, especially since he didn't fully understand what the show was about. However, "it was a breeze compared to sitting in a classroom with 30 kids," he says.

At 15 he appeared Off-Broadway in a play called The Gathering. Still he didn't envision an acting career, "because I thought it was impossible." He adds, despite worrying that it'll sound clichéd or pretentious, "I still feel that way — it's the most unreliable, tenuous profession." He was headed to college when he got the script for "Roger Dodger" — it was good enough to persuade his father, a college professor, that he should defer college. Instead he kept moving forward, to movies like "Adventureland" and "Zombieland."

He returned Off-Broadway for Lucy Thurber's Scarcity in 2007. Thurber later introduced him to Rattlestick, where Eisenberg showed Van Asselt The Revisionist, an autobiographical play about a young American visiting an older cousin in Poland.

"It's based on my own lack of appreciation of my family in America and her great appreciation for it," he says, adding that his initial visit to Poland came because he had promised his 100-year-old aunt that if he was ever near there he'd go visit the town from which she emigrated. After seeing that town he also went to visit his cousin. "I realized we were having these thematically interesting exchanges that were unique because of the language and cultural barriers."

He starred in his first play for Rattlestick, Asunscion, and loves acting in theatre, where "you have such a luxury of time so you can have long indulgent discussions about tiny moments." Still, he planned to sit out The Revisionist until Redgrave signed on and he couldn't pass up the chance to act with her. "She's so amazing," he says. "She could break up with you and you'd want to hear it again."

When the interview is over Eisenberg doesn't bolt. Instead, he sits back and steers the conversation to something more important than his play — whether the Knicks's talented but aging team is for real and can hold up for a full season.