Whether on or above Earth, hilarity is outrageously universal in TV's most popular comedy featuring four forward-thinking but socially backward geniuses. Fun discoveries multiply: Leonard learns jealousy is bad for a relationship (with Penny) but science is good for seduction (of Penny). Howard finds life in the International Space Station life is no escape from terrestrial turmoil between his mom and his new wife Bernadette. Raj meets someone special who may be a good match, if he can keep her from fleeing mid-date. And then there's Sheldon. He learns what not to say after facing harassment charges or competing for tenure at work and how Dungeons & Dragons can be the icebreaker his relationship with Amy needs.
With his friends on dates, Raj must face his loneliness. Also, Wolowitz is caught in an argument between Bernadette and his mom, even while he’s in space.
When Sheldon learns that Penny is thinking about breaking up with Leonard, he tries to intervene. Meanwhile, in space, the other astronauts pick on Howard.
Sheldon’s relationship with Stephen Hawking is threatened over a game of “Words with Friends,” and Penny secretly enrolls in a class at the local college.
Sheldon faces a crisis of confidence when he is forced to work with his nemesis, Barry Kripke; Raj and Howard buy expensive action figures of themselves.
Leonard, Sheldon and Howard give lectures on science to junior high students. The girls ditch work to go to Disneyland. Raj devises a date for Lucy that fixes their social anxiety problems.
Leonard and Sheldon hire the host (Bob Newhart) of their favorite childhood TV show to perform; Bernadette and Howard run into trouble while dog-sitting for Raj's pet.
A date between Raj and Lucy takes both of them out of their comfort zones. After a trip to Las Vegas goes awry, the girls join in on a Dungeons and Dragons game, which causes Amy and Sheldon to re-evaluate their relationship.
When Leonard receives an exciting opportunity to work overseas, Penny and Sheldon are thrown for a loop. Raj and Lucy's relationship comes to a crossroad.