Episode 1
Penny's first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant.
Episode 2
A jealous Leonard reacts to Penny's new guy by rebounding with Leslie.
Episode 3
Sheldon creates a monster when he introduces Penny to online gaming.
Episode 4
Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.
Episode 5
Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.
Episode 6
Sheldon and the gang are confused when a young grad student is attracted to him.
Episode 7
When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate.
Episode 8
Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.
Episode 9
Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.
Episode 10
Leonard asks Penny for advice when his new relationship starts moving too fast.
Episode 11
Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.
Episode 12
Penny's criticism of Wolowitz's romantic life pushes him into depression and AWOL for a fighting robot battle the rest of guys are depending on him for.
Episode 13
Sheldon creates a scientific procedure for making friends.
Episode 14
Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.
Episode 15
Leonard and Penny are drawn together after a disastrous visit from Leonard's mother.
Episode 16
A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz.
Episode 17
Leonard, Sheldon and Wolowitz are ecstatic to learn that a famous science-fiction actress (Summer Glau) is on board the train they are taking to San Francisco.
Episode 18
Penny's home business turns into a complete nightmare when Sheldon takes over.
Episode 19
Penny squares off with a new beautiful female neighbor who may become the building's "new Penny."
Episode 20
A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night.
Episode 21
Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and must stay with Penny.
Episode 22
Penny's second date with Stuart sees her making a comment that gives Leonard new hope for a relationship with her. Wolowitz realizes there's a crucial error in a NASA project he's working on.
Episode 23
The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.
