"The Big Bang Theory" Season 9 finale goes on air on May 12, Thursday. Episode 24 is titled "The Convergence Convergence" and it will feature the some highly-anticipated moments-Penny and Leonard's official wedding ceremony. Here are the detailed spoilers for the final chapter of the ninth season of the CBS' long-running sitcom. Read on to find out how it concluded. Fans can also watch the finale online via live stream for free. Scroll down for the link.

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[Spoiler alert! This article contains spoilers for "The Big Bang Theory" Season 9 episode 24 (finale) "The Convergence Convergence." Do not read further if you don't wish to know more about it.]

Fans must brace themselves for an extra special ending to the fan-favourite "The Big Bang Theory" Season 9. According to the synopsis (via Spoiler TV) for the finale (episode 24) "The Convergence Convergence," the show will finally introduce Leonard's father, Alfred. Emmy Award-winning actor Judd Hirsch will portray the role of the character who will make his first appearance in the upcoming segment.

At the same time, "The Big Bang Theory" Season 9 finale will see the return of Leonard's mother Beverly and Sheldon's mother Mary. The parents' arrival will to some chaos.

In episode 24 "The Convergence Convergence," Beverly comes face to face with her husband for the first time after they got divorced. The parents are here for Penny and Leonard's official wedding ceremony with family and friends, which never happened before.

In an interview with TV Line, "The Big Bang Theory" showrunner Steve Molaro teased what to expect when the estranged couple comes together in Season 9 finale. "I don't think things are going to get as physical [as they did on The Good Wife], but verbally she will slap him a few times," he said. Things are going to be "acerbic and caustic" between the couple.

All this happens just the night before the big ceremony. In another interview with The Hollywood Reporter, Molaro suggested that "The Big Bang Theory" Season 9 finale will end with a cliffhanger.

"We leave [the season] in typical Big Bang fashion - on bit of a cliffhanger with Leonard, Penny and Sheldon in the living room making sense of everything that's going on," Molaro told THR.

In addition, the episode 24 will reportedly see Wolowitz and Koothrappali panicking when they are contacted by the government for their guidance system. A promo video for the Season 9 finale gives a glimpse at the events of the final episode. Scroll down to watch online.

"The Big Bang Theory" Season 9 episode 24 airs May 12 at 8:00 pm on CBS. Fans can watch finale online via live stream after the television broadcast of the episode on cbs.com. Stay tuned for more spoilers and updates.