"The Big Bang Theory" didn't air an episode last week, which understandably disappointed fans. However, the show will be back with an all-new episode this week and it will involve a rift forming between Sheldon (Jim Parsons) and Leonard (Johnny Galecki) when they get into a heated argument.

The upcoming episode, titled "The Viewing Party Combustion," will reportedly show Leonard and Sheldon organizing a "Game of Thrones" viewing party for the gang. However, things will go awry when Sheldon reminds Leonard of a meeting as contracted in their roommate agreement. Leonard doesn't want to go, which will ignite a fight between the two. In a surprising turn of events, Amy (Mayim Bialik) will take Leonard's side on the situation after Penny (Kaley Cuoco) decides to back Sheldon up. In actuality, however, Amy only took Leonard's side in an effort to spite Sheldon because she's noticed that Sheldon and Penny are quite close.

Meanwhile, Howard (Simon Helberg) and Raj (Kunal Nayyar) will also have a fight of their own as the latter can't stop bragging about dating two women. He pretends he's having a hard time with the situation, but actually just wants to brag about it, which irritates Howard.

On the other hand, Stuart (Kevin Sussman) will arrive in full Jon Snow costume because Howard tricked him into thinking that they had to dress up in costume.

Promotional photos have also been released for the upcoming episode. Most of the photos show the character interacting with each other and others show Stuart dressed up as Jon Snow.

Meanwhile, here is a brief recap of the previous episode, titled "The Big Bear Precipitation."

Leonard, Sheldon, Penny and Amy went to a cabin in the woods. But when a storm interfered with their hiking plans, the group decided to play a drinking game instead. Unfortunately, Sheldon revealed during the game that Leonard has been keeping a secret bank account from Penny because he feels that she's not responsible with money. The couple initially fought over it but made up after Penny revealed that she has a secret of her own: She hates her job.

Back in the city, Raj became too involved with Howard and Bernadette's (Melissa Rauch) personal lives, which led Howard to call him out on it. After feeling bad about what they did, the couple mended things with Raj.

"The Big Bang Theory" season 9 episode 21 will air on Thursday, April 21 on CBS.