Leonard's so-called "other woman" might put a damper on his honeymoon plans with Penny in Season 9 of "The Big Bang Theory."

Before Season 8 ended, Penny (Kaley Cuoco-Sweeting) and Leonard (Johnny Galecki) agreed to elope in Las Vegas. While driving to the City of Sin, however, Leonard began having second thoughts about eloping and confessed to Penny that he had kissed another woman when he was drunk years ago. Penny assumed that he told her this in order to sabotage their plans to wed, but Leonard assured her that he's totally committed to the idea, so they agree to go through with it.

According to TVLine, Penny will meet the woman that Leonard kissed on that North Sea expedition in the new season. "Mom" star Melissa Tang has been cast as Mandy, the woman Leonard kissed. Tang, who has also appeared on one episode of "How I Met Your Mother," will be introduced on the show in Episode 2 of Season 9. As a result, this could affect Leonard and Penny's potential honeymoon.

Earlier this summer, showrunner Steve Molaro revealed that the season premiere will pick up shortly after the point where Season 8 left off while speaking to TVLine's Michael Ausiello.

"We pick up a few hours after the eighth season finale," said the executive producer at the 2015 San Diego Comic-Con. "So, Leonard and Penny were heading to Vegas, and we're going to catch up with them right there."

Zap2It published the description for the first episode of the new season. It states that "Brilliant Sheldon is confronted by a mystery of the universe he cannot unravel: when a woman wants time apart to think, exactly how much time does that mean, and is there any way to hurry the process along? In Las Vegas, Penny and Leonard march closer to marching down the aisle, but has Penny gotten over Leonard's infidelity? And if so, will he do anything to un-get her over it?"