There will be a lot to look forward to when Season 9 of "The Big Bang Theory" kicks off next month, including guest appearances from Sheldon's mom and Penny's father, as well as the mystery behind Sheldon's engagement ring.

As fans will recall, Season 8 of the popular CBS comedy finale ended with a major cliffhanger, as Sheldon and Amy's slow-moving relationship seem to come to a shocking halt. After dating for years, Amy told Sheldon that she was fed up with their lack of growth and needed space to "step back and re-evaluate" their relationship. Devastated by the breakup, Sheldon began talking to the Gollum figurine on his desk and pulled out an engagement ring he apparently planned to give Amy. Meanwhile, Penny and Leonard agreed to elope in Las Vegas.

The producers behind the hit TV series told Entertainment Weekly that "The fate of the ring Sheldon held at the end of the episode -- and the fate of other rings -- will be revealed" in the new season.

In addition, actress Laurie Metcalf will reprise her role of Sheldon's mother during the Season 9 premiere, while Keith Carradine will be featured as Penny's father in Season 9's third episode.

While speaking at the 2015 Comic-Con in San Diego in July, actress Mayim Bialik revealed that the new season will start just hours from where the finale left off.

"All they've told us is that Episode 1 of Season 9 picks up a few hours after Season 8 ended," she told Entertainment Tonight.

Kunal Nayyar also opened up about his character Raj and his romance with his girlfriend Emily, played by Laura Spencer.

"He's kind of scared of her, but I think that kind of turns him on," said Nayyar, adding that Emily is "going to take him to places he's never been."

Furthermore, actress Kaley Cuoco-Sweeting told ET at the Beverly Hilton's 60th anniversary bash that the upcoming season is "off to a great start."

"Between Leonard and Penny... All the dreams came true for me," she said.

Season 9 of "The Big Bang Theory" will premiere on Monday, Sept. 21 on CBS.