The Big Bang Theory
The Season 10 premiere of The Big Bang Theory will introduce Penny's mother and brother.Facebook/The Big Bang Theory

Season 9 of CBS sitcom The Big Bang Theory ended on a major cliffhanger with Sheldon's mother and Leonard's father going off to their hotel for a nightcap and switching off their mobile phones, thereby hinting that the duo may have retired early to have sex. The new season, which will premiere on Monday, picks up from there, with Leonard and Sheldon wondering if they would eventually become brothers.

Season 10 episode 1 of The Big Bang Theory is titled The Conjugal Conjecture and it will finally reveal what happened between Mary and Al after they retired from the rehearsal dinner. The synopsis for the episode does not reveal much other than to state that everyone shared an awkward moment due to Mary and Al's disappearance. But a leaked description of the episode on The Big Bang Theory Wikia revealed that Mary and Al do not have sex. They spent the night getting to know each other and arrived at a decision to continue their relationship.

As expected, Sheldon will not be too enthusiastic about his mother dating, but Mary does not get discouraged.

The episode will also feature Penny and Leonard's wedding and according to the information on The Big Bang Theory wikia, it is a beautiful scene. Here's what happens.

They are outside at a park. It is lovely. Amy is playing the harp. Bernie is up front to officiate. Everyone is seated. Stuart walks in and sits in the empty seat between Leonard's parents. Penny has on a gorgeous wedding dress that comes to her knees, simple but really beautiful. They actually say some beautiful words to each other.

The synopsis for The Conjugal Conjecture reads: "After Sheldon's mother and Leonard's father share an evening together, everyone deals with an awkward morning the next day. Also, Penny's family arrives for the wedding ceremony, including her anxiety-ridden mother, Susan, and her drug dealing brother, Randall."

Season 10 episode 1 of The Big Bang Theory can be watched online on CBS' official page or via its app.