The Big Bang Theory: Season 4
The Big Bang Theory Season 4 continues the overarching saga across 24 episodes.
Season 4 Lore Primer
Key plot threads, lore context, and character stakes you need to remember before diving into this season.
- Picks up essential narrative continuity directly following the events of The Big Bang Theory Season 3.
- Character alliances, factions, and personal loyalties undergo significant shifts under escalating stakes.
- Addresses unresolved cliffhangers and thematic mysteries introduced during previous seasons.
- Establishes the primary seasonal conflict that drives serialized character arcs toward the finale.
Season overview
The Big Bang Theory Season 4 continues the overarching saga across 24 episodes.
Episode Guide
Season 4 Progress Shield
The Robotic Manipulation
Sep 23, 2010
Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm.
The Cruciferous Vegetable Amplification
Sep 30, 2010
Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.
The Zazzy Substitution
Oct 7, 2010
The guys are concerned as Sheldon searches for an alternative to human companionship.
The Hot Troll Deviation
Oct 14, 2010
An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.
The Desperation Emanation
Oct 21, 2010
Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his.
The Irish Pub Formulation
Oct 28, 2010
Leonard keeps an affair a secret from Sheldon, Howard and Raj.
The Apology Insufficiency
Nov 4, 2010
Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.
The 21-Second Excitation
Nov 11, 2010
While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.
The Boyfriend Complexity
Nov 18, 2010
Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.
The Alien Parasite Hypothesis
Dec 9, 2010
Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.
The Justice League Recombination
Dec 16, 2010
The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.
The Bus Pants Utilization
Jan 6, 2011
Leonard's idea for a smartphone app derails his friendship with Sheldon.
The Love Car Displacement
Jan 20, 2011
Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.
The Thespian Catalyst
Feb 3, 2011
Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend's girlfriend.
The Benefactor Factor
Feb 10, 2011
A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.
The Cohabitation Formulation
Feb 17, 2011
As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.
The Toast Derivation
Feb 24, 2011
Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.
The Prestidigitation Approximation
Mar 10, 2011
Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.
The Zarnecki Incursion
Mar 31, 2011
Sheldon's online-game account is hacked by Todd Zarnecki, who then proceeds to steal all his items prompting the guys to go on a quest to retrieve them. Penny, Bernadette and Amy
The Herb Garden Germination
Apr 7, 2011
Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to even higher level.
The Agreement Dissection
Apr 28, 2011
When Leonard spends too much time in the shower with Priya, Sheldon charges Leonard with two violations of the roommate agreement. However, before he can get too far, Priya uses he
The Wildebeest Implementation
May 5, 2011
Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.
The Engagement Reaction
May 12, 2011
When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.
The Roommate Transmogrification
May 19, 2011
When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.