It's that time of the year. "The Big Bang Theory" ended its ninth season on a cliffhanger of sorts, which means fans will have to wait a while to find out what really happened between Sheldon's (Jim Parsons) mom, Mary (Laurie Metcalf), and Leonard's (Johnny Galecki) dad, Alfred (Judd Hirsch).

The season 9 finale saw Leonard's parents and Sheldon's mom visiting town to witness a formal wedding ceremony for Leonard and Penny (Kaley Cuoco). In a surprising turn of events, Mary and Alfred ended up getting along better than expected and even retreated to the same hotel room for a nightcap. The rest was left open-ended, but the general assumption is that they hooked up—the very notion of which disturbs Leonard and Sheldon.

So what will happen in season 10?

Having already been renewed for another season, "The Big Bang Theory" will pick up from where the finale left off. Viewers will find out the truth when it premieres. Aside from that, the new season may be introducing some new faces.

"It's a little early to say for sure, but we would very much like to meet Penny's mom and her brother, as well," showrunner Steve Molaro told TVLine. A current rumor going around is that Lisa Kudrow will be playing the role of Penny's mother, although nothing has been confirmed.

As for other family members, Howard's (Simon Helberg) father was also brought up when Molaro spoke to The Hollywood Reporter. And although he's not a priority right now, "it's always floating around."

The new season may also feature the guidance system storyline, which involves Leonard, Sheldon and Howard. As fans know, the Air Force is interested in their project. Additionally, Howard and Bernadette (Melissa Rauch) are expecting a child together, which will surely be a major arc in season 10. Another plausible arc involves Sheldon and Amy (Mayim Bialik) moving in together, which is a huge step for them, although Molaro says that it's "so soon."

There's also the idea that season 10 may be the show's last, but Molaro says he won't look at it as the end just yet. Seeing as the season will consist of 24 episodes, there will be a lot of room to breathe for now. However, if it does turn out to be the final season, Molaro already has an idea in mind on how to go about the series finale.

"The Big Bang Theory" season 10 is expected to premiere in the fall.