Rachel confronts her mother, while Tina faces an identity crisis. New Directions were given a task to sing Lady GaGa songs.
Episode: 20
The Relationship Diremption
Sheldon has a personal crisis when he decides string theory is a waste of his time; a double date ends in embarrassment for Howard.
The Tenure Turbulence
The girls get involved when Leonard, Sheldon and Raj LL compete for tenure at the University.
The Transporter Malfunction
Penny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock. Meanwhile, Raj decides he has met the “Future Mrs. Koothrappali” after his parents set him up on a date.
The Herb Garden Germination
Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to an even higher level.
The Spaghetti Catalyst
When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.
The Hofstadter Isotope
When a fellow comic book enthusiast hits on Penny it leads to Leonard and Howard going to a bar's on Ladies' Night.
Makeshift
L has bugged the secret meeting in the Yotsuba corporation and the task force is divided between those who want to stop the killing by arresting the 7 members of the Yotsuba corporation and those who want to wait to know who is actually Kira.