Big Bang Theory season 9 episode 21
Leonard, Penny, Amy and Sheldon in The Big Bang Theory season 9CBS

Sheldon Cooper and Leonard Hofstadter will engage in another heated debate when The Big Bang Theory season 9 returns from a week-long hiatus. Episode 21 titled The Viewing Party Combustion will air on 21 April at 8pm EST on CBS Network.

The official synopsis reads as follows:

Penny, Amy, Bernadette, Howard and Rajesh will be forced to choose side after Leonard and Sheldon's petty argument about the Roommate Agreement turns into a heated debate. It is nothing new for the two, as they have fought over the Sheldon-crafted document many times in the past.

Warning: Spoilers ahead

According to a leaked report, in the episode, Sheldon will remind Leonard about their quarterly roommate agreement meeting but Leonard is less than interested in having one. This will lead to a big argument between the two friends. While Penny will take Sheldon's side, Amy sides with Leonard and says that she understands Leonard's perspective and drops a bomb that she never liked her Relationship Agreement meetings with Sheldon either.

Sheldon gets very mad at Amy for siding with Leonard and the gang gets divided into two, as Sheldon and Penny go to Apartment 4B to watch Games of Thrones and Raj joins them. And the rest stay over at Apartment 4A with Leonard and Amy.

So, how do you think this fight will be resolved? Will Leonard attend the quarterly roommate agreement meeting? Let us know in the comments below. The Big Bang Theory airs Thursdays at 8pm on CBS.