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. Also, Denise and Stuart overstay their…

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. Also, Leonard wants to be the…

Penny tries to seduce an abstaining Leonard to ruin his “donation” for her ex-boyfriend, Zack, and his wife, Marissa. Also, Wolowitz, Bernadette, Anu and Koothrappali turn Koothrappali’s canceled bachelor party…

Penny’s ex-boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard for help. Also, Koothrappali attempts to mend things with his ex-fiancée, Anu.

Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy. Also, Koothrappali catches Anu with her ex-boyfriend, and Stuart doesn’t want to move…

Sheldon tries to bond with Amy’s father, but when Howard lures Mr. Fowler away with magic tricks, Sheldon has no choice but to bond with Mrs. Fowler. Raj and Anu…

When Howard dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny’s Halloween party. Leonard is shocked that Penny doesn’t remember their first kiss.

The Wolowitzes’ life gets complicated when Stuart starts bringing his new girlfriend home. Penny and Leonard talk about starting a family. Raj explores an arranged marriage.

When Sheldon won’t tell anyone why he’s never mentioned his childhood best friend, Leonard takes matters into his own hands. Bernadette and Penny take out Raj’s fiancée for dinner to…