The 20th episode of Season 6 of "The Big Bang Theory" airs Thursday night. You can watch "The Tenure Turbulence" at 8 p.m. ET on CBS. If you miss the live airing of the show, you can also catch it later this week at CBS.com.

Before you watch Thursday night's Season 6 episode of "The Big Bang Theory," here is a look at some spoilers from the last new show.

As thetwocentscorp.com notes, the last new episode of "The Big Bang Theory" was a bit more serious than usual. Sheldon (Jim Parsons) cleaned out Howard's (Simon Helberg) closet and found a note written by the latter's absent father. The letter had been left for Howard when he was 18, but he had never opened it. The scientist ultimately decided that he wanted to keep that part of his life in the past and burned the letter in the sing.

However, Howard's wife, Bernadette (Melissa Rauch), decided that she wanted to know what her husband's father had written. She then realized that Sheldon had read the contents of the note to determine how to sort the letter in the newly-organized closet. So, she, Penny (Kaley Cuoco) and Amy (Mayim Bialik) decided to try to get the information out of him. Eventually, Sheldon admitted what was in the contents of the letter.

This plot then merged with the other storyline of the last episode of "The Big Bang Theory." As Hypable notes, Leonard (Johnny Galecki) and Penny were jealous of Howard and Bernadette's dinner party from earlier in the show and decided to throw one of their own.

When the ladies arrived at that party, they immediately revealed that they knew what was in Howard's father's letter. Sheldon thus had to spill the beans to Leonard and Raj (Kunal Nayyar) as well, so Howard was now the only one unaware of what his father wrote.

Howard at first was angry when he discovered that his friends went behind his back to learn the contents of the note. However, the group came up with an idea to give Howard a hint of what it said without giving it all away. Each person gave a sentence or two summary of what could have been in the note, with only one of those statements actually being true. Since all of the descriptions revealed a loving and caring message, Howard decided he did not want to know what was actually in the letter.

Spoilers indicate that Thursday night's episode of "The Big Bang Theory" appears to be a bit more light-hearted. Per CBS.com, Sheldon, Leonard and Raj will fight for tenure at the university they work at, with the ladies of the series getting involved as well. Per TVLine, Regina King will reprise her role as a school administrator.

Did you watch episode 20 of Season 6 of "The Big Bang Theory? Post your thoughts on the show in our comments section below.

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