The Big Bang Theory

Like any good FBI agent would, Eliza Dushku did her recon work before heading to The Big Bang Theory for her guest spot.

"I am a fan, but I have to be honest. I Wikipedia-ed each of their characters to see things that have been revealed and things that might be in their file so I would get lines that I wouldn't have made the connection to because I haven't watched every single episode," Dushku tells TVGuide.com. "When they said little things, I could raise an eyebrow or have a light bulb go off. Wikipedia has such an intense rundown on all the characters and all the actors. I mean, I really felt like I could go in as an FBI agent who had all my information on them."

The Big Bang Theory geeks out for Eliza Dushku

On Thursday's episode (8/7c on CBS), Dushku will be seeking more information from the guys. She plays Angela Page, an FBI agent tasked with questioning Wolowitz's buddies so he can get security clearance for a gig in the Defense Department. Needless to say, things don't go smoothly. For starters, Raj (Kunal Nayyar) — as he usually does in front of women — clams up in front of Angela from the get-go. "Raj is uncomfortable from the moment I walk in," Dushku says. "He's my first interviewee and he sets the tone for the blunders and insanity. He was great. Kunal plays that part so well."

But it's Sheldon (Jim Parsons) who puts Wolowitz's chances in jeopardy after he overshares too many details about the resident ladies' man.

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"It's typical Sheldon! He can't help himself. He tells me more than he should and more than I want to know," Dushku says. "Angela's a no bulls--- type of person. It's not terrorism she's investigating, but one of the lighter parts of her job is having to interview these guys, and they are giving her the runaround, and she's trying to filter through their neuroses and get a few facts, so she tries to stay on course. But Sheldon does come back and we rehash it out."

Whether or not Wolowitz (Simon Helberg) gets clearance remains to be seen, but Dushku — who follows fellow sci-fi babes Battlestar Galactica's Katee Sackhoff and Terminator: The Sarah Connor Chronicles' Summer Glau in appearing on Big Bang — says the episode comes "full circle" by the end.

For the actress, the role is a 180 from the intense, dramatic fare she's become known for after starring on Buffy the Vampire Slayer, Tru Calling and Dollhouse. She was offered a part on the show "six or seven months ago," but she and executive producers Chuck Lorre and Bill Prady all felt Angela is the better — and right — fit for her.

"I was excited then, but this is better than what might've been. I love comedy. ... I feel like I really want to get back into that playful side of me because it's so much of who I am," she says. "I think back to Bring It On and Jay and Silent Bob Strike Back. [Big Bang] was so much fun. I love the format and the schedule for a half-hour multi-camera. You rehearse, you play around with it and then it's the live audience night. You have so much adrenaline. I had my family and friends in the audience [and after] my first take, they were like, 'Yeah, your first take — you were a little stiff.' But we get to do it again, unlike theater, so once I got through that, it was very natural and very fun."

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While she would never say no to a well-written dramatic role, Dushku says she's definitely looking to do more comedy and is "re-strategizing" what's next, as she's working more as a producer.

And if more comedy means more Big Bang, that's perfectly fine with her.

"After the unbelievable time I had, I hope there's a high chance of that happening!" she says. "It's so ironic because I didn't have a scene with Wolowitz ... or Kaley [Cuoco], who was back from her leg injury. They had her in the final scene, behind the bar, and they were hiding the broken leg. She's super cute! I wish we had scenes together. ... Maybe next time? I would love to come back."