The Big Bang Theory's tenth season comes to an end Thursday night with an episode that mixes big laughs with big character moments.

Viewers with good memories will have an idea of what's coming, but still, there's a big surprise coming at the end of "The Long Distance Dissonance."

"I think it's funny and fast-paced and ends with a real wallop," showrunner Steven Molaro tells TVGuide.com.

The episode picks up with Amy (Mayim Bialik) away at Princeton and the gang concerned about Sheldon (Jim Parsons) hanging out with Ramona Nowitzki (Riki Lindhome), who last appeared in Season 2 as a graduate student with a big crush on Sheldon and returns to Caltech for her postdoc.

Back then, Sheldon was completely oblivious to Ramona's very obvious romantic interest, and that hasn't changed. But Sheldon's friends are very aware, as is Amy, who's unhappy with what's going on across the country from her.

Molaro gave us the scoop on how the episode came together and what the future of The Big Bang Theory might hold.

Riki Lindhome and Jim Parsons, <em>The Big Bang Theory</em>Riki Lindhome and Jim Parsons, The Big Bang Theory

TVG: What do you think is the funniest moment from the finale this year?

Molaro: Amy on Skype yelling at Penny (Kaley Cuoco) and Bernadette (Melissa Rauch) was funny to me from the minute we wrote it to watching them rehearse it all week. That one joke about she's "been whacking that ketchup bottle, and now all this Ramona chick has to do is tip it over and point it at her fries," that was from one of our writers, Eric Kaplan, and we thought that was the funniest thing from the minute it went into the script to every time Mayim said it.

How did you come to the decision to bring Riki Lindhome back?

With Amy away for a few months, we liked the idea that Sheldon was essentially on his own for the first time as far as what we've seen on Big Bang Theory, living in an apartment by himself, his girlfriend who he's very attached to is now far away, and we wanted to explore what that would mean for his character. One of the things we thought could be interesting based on that was what would happen if another woman came along while Amy was gone and what would that do to Sheldon as well as his group of friends.

And then once we had that thought, what if another woman comes sniffing around after Sheldon, the next question was who would that woman be? And we had always loved when Riki played Ramona in Season 2, so we quickly called her to see if she was available, and she was, and it happened very quickly after that. Everything fell into place. We love her.

Riki Lindhome, <em>The Big Bang Theory</em>Riki Lindhome, The Big Bang Theory

You've done a lot of finales by now. What's special about this one?

What I love about this finale is it really focuses on all of the gang as a family, as a group supporting each other. Everybody has lots of fun stuff to do. I think it's funny and fast-paced and ends with a real wallop.

Ooh, ends with a real wallop! What can you tease about that ending? Are people going to be surprised by what they see?

We try to do things that keep us excited and nervous, and I think that helps us keep the show fresh. I think this episode is among them. There's an outsider floating around Sheldon and making a real play for him while Amy's gone. There are a lot of exciting things in play.

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The show was just renewed for another two seasons. Do you think you'll keep going after 12?

All I know is we're doing the next two and that'll be our focus. I can't look beyond that. Right now our goal is to make the next two years as good as they can possibly be.

Would you like to?

I really just need to focus on the next two. I love this show, I love working with all these actors, but it's enough right now to worry about the 48 we have to go. We've managed to keep it good after 10 years, and now we're going to keep it good for 12.

The Big Bang Theory's Season 10 finale airs Thursday, May 11 at 8/7c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)