"The Big Bang Theory" (TBBT) cast, which includes Kunal Nayyar (Dr Rajesh "Raj" Koothrappali), Jim Parsons (Dr Sheldon Cooper) and Johnny Galecki (Dr Leonard Hofstadter), will be featured in the sitcom's new episode titled "The Separation Triangulation." It will air in the US on Jan. 18. It will show Raj dating a woman who's already married. Unfortunately, Raj wasn't aware of it and the woman's husband is furious when he finds out about it.

Spoiler alert: This article has additional 'The Big Bang Theory' spoilers 2018. Read on if you want to know more about 'The Separation Triangulation.'

"The Big Bang Theory" season 11, episode 14 will show Raj finding out that the new woman he's dating is married. According to a CBS press release, he will find himself stuck between a domestic drama when the woman's husband finds out about them and is very upset about it. As for Sheldon, he will rent his old room back because he wants a quiet place to work. However, he will also drive Leonard crazy by being an ideal tenant.

Mark Cendrowski directed this episode. Its story was written by Maria Ferrari, Eric Kaplan and Chuck Lorre. The teleplay was written by Tara Hernandez, Steven Molaro and Steve Holland.

'The Separation Triangulation' stars

According to the Internet Movie Database (IMDb), the guest stars that will appear in "The Separation Triangulation" are Walton Goggins of "Justified" and Beth Behrs of "2 Broke Girls." They will be joined by the other "The Big Bang Theory" cast members such as Mayim Bialik (Dr Amy Farrah Fowler), Simon Helberg (Howard Wolowitz), Melissa Rauch (Bernadette) and Kaley Cuoco (Penny).

'The Big Bang Theory' episodes: 'The Solo Oscillation'

The episode before "The Separation Triangulation" is "The Solo Oscillation," which will air on Thursday on CBS. It will feature Sheldon kicking out Amy to work alone. Plus, Sheldon will find Penny scientifically inspiring. As for Howard, he will be replaced by Bert the geologist (Brian Posehn) in the Footprints on the Moon band. Mark Cendrowski directed "The Solo Oscillation," while Jeremy Howe, Eric Kaplan and Maria Ferrari wrote its teleplay. Meanwhile, Anthony Del Broccolo, Chuck Lorre and Steve Holland wrote its story.

"The Big Bang Theory " airs on Tuesdays after "The Block" in Australia on Channel Nine. In the US, it airs on Thursdays 8-8:30 pm ET/PT on CBS. Stay tuned for more TBBT spoilers and updates for 2018.