Walt and his family wait for news after he undergoes a PET-CT scan. Walt follows Saul’s advice; Jesse’s relationship with Jane is put on hold when he and Walt head…

Sheldon winds up in traffic court when he gets a ticket because of Penny.

Leonard can only bring one guest on a trip to see CERN’s Large Hadron Collider (the world’s largest and highest energy particle accelerator) in Switzerland on Valentine’s Day.

Sheldon’s search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

Leonard is aghast to find out a secret of Penny’s: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrappali in picking up a girl at a university mixer.

A Christmas visit from his mother has Leonard discovering she’s kept a lot of news from him that she shares with Sheldon and worrying if she’ll approve of his romance…

Penny gets help from Sheldon in order to understand what Leonard’s work is, while Wolowitz develops a jealousy when Leonard starts hanging out with his new girlfriend.

Walt and Jesse seek advice from a shady attorney when Badger gets in trouble with the law; the DEA believes they have caught up with “Heisenberg” ; Hank returns.

After he’s humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.

Sheldon becomes Leonard’s teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj’s friendship.

After overhearing that Wil Wheaton is entering a trading-card competition, Sheldon decides to enter it himself. Meanwhile, Penny sets up one of her friends on a date with Wolowitz.

Raj must find a new job or be sent back to India, but Sheldon has a solution, which leaves Leonard and Penny dealing with Howard as a third wheel.

Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.

Jesse and Walt discuss expanding into new territories; Hank struggles to fit in; Skyler pursues a new job opportunity; Jesse gets to know his landlord.

Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books on a bet to determine the species of a cricket.

When Sheldon learns the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens…

Walt’s secret is in jeopardy when Skyler thanks Gretchen for paying for his treatment.

Hank suffers from the aftermath of his encounter with Tuco. Meanwhile, Jesse hires a crew to get their product out on the streets.

Walt attempts to reconnect with his family, while Jesse struggles to rebuild his life.

Walt and Jesse become short on cash when they try to cover their tracks. Meanwhile, the DEA has a lead that could them straight to Walt and Jesse.

Walt and Jesse find themselves in close quarters with an unhinged Tuco. Marie and Hank comfort Skyler, who is distraught over Walt’s disappearance. Hank pays a visit to Mrs. Pinkman…

Walt and Jesse are vividly reminded of Tuco’s volatile nature, and try to figure a way out of their business partnership. Hank attempts to mend fences between the estranged Marie…