Bernadette receives her PhD, and the friends then tease Howard about being the only one among...
Howard decides to tell his mother that he and Bernadette are engaged - but she later collapses,...
Amy and Penny use Bernadette to spy on Leonard and Priya after the couple invite her and Howard...
Sheldon is infuriated when Priya uses her legal knowledge to find a loophole in the room-mate...
Amy and Sheldon start a gossip experiment to see how quickly rumours spread among the gang,...
Sheldon is distraught when his online gaming account is hacked, so his friends decide to find...
Leonard faces the difficult decision of choosing between his relationship with Priya and his...
Sheldon decides to make a new set of friends as he is depressed that the group's social world...
Howard is torn between his relationship with Bernadette and pleasing his mother - and comes up...
Leonard is forced to consider how far he is willing to push himself in the name of science when...
Sheldon agrees to participate in a series of short lectures at the university, but is worried...
Tension mounts when the gang attends a weekend science conference. Howard becomes argumentative...
Leonard's ingenious idea for a new smart-phone app puts pressure on his friendship with...
The guys have fun at the expense of Penny's boyfriend Zack, but later try to make amends by...
Amy finds she has romantic feelings for Penny's former boyfriend Zack, while Raj and Howard...
Penny's dad pays a visit and Leonard discovers she told her parents they were back together, so...
The friends set up camp outside a cinema to get tickets for a new cut of Raiders of the Lost...
Leonard vows to be more self-assured around women, believing his problem attracting a...
Raj's sister Priya visits the gang, causing tension when Leonard tries to cover up the fling he...
Leonard is depressed that everyone seems to be paired off except him, and takes desperate...
An embarrassing secret from Howard's past comes to light as he tries to win back ex-girlfriend...
Sheldon breaks up with Amy and turns to cats in his search for an alternative to human...
Sheldon tries to extend his lifespan, concerned he will not be around long enough for his...
Penny is stunned when Sheldon announces he is about to go on his first-ever date, and is even...
