In the last season of Big Bang Theory, Leonard got assigned to a new project where he would be off at sea. Sheldon and Penny creates an unlikely bond. Here's the synopsis:
“The Hofstadter Insufficiency” and “The Deception Verification” –- Sheldon (Jim Parsons) and Penny (Kaley Cuoco) share intimate secrets while Leonard (Johnny Galecki) is away at sea, later, Sheldon’s feelings are crushed when Leonard returns. Meanwhile, Raj (Kunal Nayyar) gets consoled about his ex-girlfriend and Wolowitz’s (Simon Helberg) relationship with his mother causes an unusual threat to his masculinity. Regina King returns as Mrs. Davis, the University’s Director of Employee Relations, and Kevin Sussman returns as Stuart, the comic book store owner.