Leonard realizes he's the only one without a girlfriend, while Sheldon wants to get rid of his.
Tension runs high when everyone is staying at the same hotel for a science event and Bernadette runs into her ex-boyfriend (guest star RICK FOX three-time NBA champion with the Los Angeles Lakers).
Sheldon wants Penny to give him acting lessons, hoping that they will help him become a better teacher. Meanwhile, Koothrappali fantasizes about his best friend's girlfriend.
As Wolowitz contemplates taking things with Bernadette to the next level, he must choose between his girlfriend and his mother. Meanwhile, Leonard rekindles his relationship with Raj's sister, Priya.
Penny asks Leonard to lie to her father, Wyatt (guest star KEITH CARRADINE), while Howard, Raj and Bernadette pull an all-nighter at a telescope.