Jodi Lyn O'Keefe with Kunal Nayyar, The Big Bang Theory

Jodi Lyn O'Keefe is going from Prison Break bad girl to sitcom working girl, with a guest-starring turn on this Monday's The Big Bang Theory (8 pm/ET, CBS). O'Keefe gave us a look at exactly who of the Big Bangers she'll "do business" with, as well as shared a glimpse at her return to prison.

TVGuide.com: Had you seen The Big Bang Theory before?
Jodi Lyn O'Keefe: Oh yes. I'm [series creator] Chuck Lorre's biggest fan, and have been working with him my whole life. He usually brings me on to the shows that he's doing to either guest-star or recur. I couldn't be happier. 

TVGuide.com: Right, you've been on Two and a Half Men...
O'Keefe: Twice, and I recurred on Dharma & Greg.... I adore Chuck — he is one of the funniest men in Hollywood. He really knows how to write. 

TVGuide.com: Let's talk about Big Bang Theory's Mikayla.
O'Keefe: I'm a hooker. 

TVGuide.com: Um, she's a "working girl"?
O'Keefe: A working girl, yes. Am I not allowed to say hooker? [Laughs

TVGuide.com: Who does she angle to "do business" with there in Vegas?
O'Keefe: Raj. 

TVGuide.com: But it's a depressed Wolowitz who prompts the boys to make the road trip. What's she doing getting up in Koothrapali's grill?
O'Keefe: Well, he's the one I meet first! 

TVGuide.com: Is he sufficiently drunk to be able to talk to her?
O'Keefe: Yeah, he gets a couple words out. 

TVGuide.com: Do they ... arrive at an agreement?
O'Keefe: They may. It's pretty funny how it all plays out. 

TVGuide.com: Big Bang is a very funny show.
O'Keefe: Oh my god.... Jim Parsons (Sheldon) is the funniest man on the face of the planet. 

TVGuide.com: He's not in the Las Vegas storyline, though.
O'Keefe: No, but [the episode is set] half in Vegas and half back at his place. So he's there, trust me!

TVGuide.com: You're back on Prison Break, at least in the standalone movie being released to DVD. When did you shoot that?
O'Keefe: We just finished it actually, at the end of the season. 

TVGuide.com: Gretchen was in fact taken into custody and imprisoned? She couldn't wiggle her way out of that last predicament?
O'Keefe: No. I was hoping she would, but it's nice to come back for these last two episodes. 

TVGuide.com: The set-up isn't about her orchestrating a prison break, however. It's about somebody else...
O'Keefe: Yes, the central set-up is about somebody else being in prison, and what that's going to be like. It's kind of cool because this is like a rewind. 

TVGuide.com: Meaning, whereas the series' actual finale ends with a four-year flash-forward this movie place during that time gap.
O'Keefe: Exactly. 

TVGuide.com: Is Gretchen even harder in prison, or has it humbled her?
O'Keefe: She's pretty hard in prison, though she's keeping to herself. She has one goal in mind — to get out and see her daughter. But she has been very quiet, and has established herself as someone not to mess with. The inmates all leave her alone, so she must have done some fighting when she first got in!