Bernadette and Wolowitz leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; Koothrappali makes a new friend; the gang travels together into an uncharted future.

The Big Bang Theory

The Stockholm Syndrome

The Change Constant

Leonard is pleasantly surprised when Beverly comes to visit and she's genuinely kind to him, until he finds out the real reason she's there; Denise and Stuart overstay their welcome at the Wolowitz house.

The Maternal Conclusion

Kripke has proof that Dr. Pemberton plagiarized his thesis in college, and Sheldon and Amy aren't sure if they should turn him in or not; Wolowitz learns that Bernadette wasn't the only waitress at the Cheesecake Factory who had a crush on him.

The Plagiarism Schism

Koothrappali is worried people won't take him seriously in his own field after publishing a paper that suggests he may have discovered alien life; Leonard wants to be the principal investigator on a plasma physics study.

The Decision Reverberation

Physicists and best friends Leonard and Sheldon learn about the social aspects of life through their relationships with the free-spirited beauty who moves in next door.

Sheldon and Amy's honeymoon runs aground in New York; Penny and Leonard discover they are uncomfortably similar to Amy's parents; Koothrappali insults physicist Neil deGrasse Tyson and starts a Twitter war.

S12 E1 | The Conjugal Configuration