Sheldon wins a National Science Foundation grant to pay for a three-month expedition to the North Magnetic Pole. His plan is to detect the magnetic monopoles in a way that would prove the validity of string theory. After some hesitation, he decides to go, and wants his three friends to join him.

Howard is celebrating the launch of his “space toilet” (a special latrine for the ISS) by buying all of his friends new comics. Stuart tells Leonard he is having a second date with Penny and asks for advice.

Leslie Winkle breaks up with Howard, and he becomes depressed. Leonard and Raj decide to take him on a trip to Las Vegas in order to cheer him up. While in Vegas, a prostitute named Mikaela begins talking to Raj. He and Leonard eventually decide to hire her to pose as a Jewish woman and [...]

While Stuart, a fellow comic book-loving pal of the guys romances Penny, Leonard and Wolowitz venture out into the world of “Ladies’ Night” at a local bar. Penny needed a comic book for her nephew’s birthday, so she goes to the comic book store with the guys.

The former tenants of unit 5A, the apartment above Leonard & Sheldon’s, move out, replaced with an attractive woman named Alicia. Alicia, like Penny, is an actress, but a more successful one. by flirting with the guys, she manages to wrap Leonard, Wolowitz, and Raj around her finger; she even gains Sheldon’s approval after an [...]

Penny has developed a home-made hair barrette called the “Pennyblossom,” which has proven unexpectedly popular via word-of-mouth. She consults Sheldon for help in developing her product into a workable home business, which involves streamlining the creation process via assembly line and the episode’s titular work songs. Leonard, Howard, and Raj add their own ideas for [...]

A train trip to a conference in San Francisco takes a major detour when Leonard, Sheldon, Wolowitz, and Raj discover that their favorite sci-fi actress in all the land, Summer Glau, is on board. But the fanboy frenzy quickly gives way to a heated mass debate when they realize one of them will have to [...]

A paintball game leads to a fight between Penny and Sheldon, and romance for Wolowitz and Leslie. Penny accidentally shoots the paintball gun at Sheldon’s couch cushion (his “spot”, his “only point of consistency in an ever-changing world”), and she and Leonard have a hard time getting it cleaned. They try just turning it over [...]

A phone call from Leonard’s mother, Dr. Beverly Hofstadter, leads to problems all around as childhood problems emerge from both Penny and Leonard. Penny bumps into Leonard’s mom while doing laundry, and she reveals she is a psychiatrist and neuroscientist. By the time they reach Leonard’s apartment, Penny is in tears after being psychoanalysed. Sheldon, [...]

Penny is unable to pay her rent due to an acute case of destitution, so Sheldon does the logical thing and loans her some money. Despite Sheldon’s complete ease with her indebtedness, however, Penny becomes neurotic and prone to lashing out over money concerns. Leonard tries to help Penny solve her problem and in the [...]

Socially awkward, Sheldon develops a scientific procedure for making friends. He needs to use an open science grid computer that is in Barry Kripke’s office, but Leonard tells Sheldon that only Barry’s friends can use it. After repeated rebuffs from Kripke, Sheldon finds a children’s book in the bookstore (where he is hurried out by [...]

When Penny’s comment about Wolowitz’s love life sends him into a depressed stupor, his friends lose their most important team-mate in an upcoming fighting robot competition. When Sheldon accepts a challenge for a one on one fight, pitting their robot, M.O.N.T.E., against that of their co-worker, Barry Kripke Leonard tries to get Howard back on [...]

Leonard meets his intellectual superior in award winning scientist David Underhill (Michael Trucco). Underhill is the total opposite of Leonard: handsome, charming, and cool. He’s the whole package of brains and looks which initially doesn’t sit well with Leonard. Although when Hill asks for Leonard’s help in research he is undertaking, he happily jumps at [...]

Stephanie has moved in with Leonard and Sheldon, according to their roommate contract, though Leonard denies that she is living with them. She tries helping Sheldon with a ringing in his ear, but is unable to help him. After Sheldon walks Leonard through the changes that must be made now that Stephanie has officially moved [...]

Sheldon is concerned that Stephanie is the only girl Leonard has dated that he “finds tolerable”. He tries to force himself into conversations with “urban slang” to “help” Leonard in the relationship with Stephanie, as “history suggests” he will fail (“You’re [Leonard is] Kirk, I’m [Sheldon is] Spock, Wolowitz is Scottie, Koothrappali is the guy [...]

A smitten Wolowitz thinks he’s found his soul mate–until the woman, Dr. Stephanie Barnett (Sara Rue), meets Leonard. Wolowitz invites Stephanie to drive the Mars rover, which winds up stuck in a ditch. Eventually, to hide evidence of what he has done, Wolowitz destroys all the security tapes and hard drives he can find relating [...]

When Penny’s cable gets cut, she starts coming over to the guys’ apartment to watch America’s Next Top Model. However, after Sheldon bans her from the apartment for a series of petty infractions (touching his food, sitting in his spot, and sending him “email humor”), Penny taunts him at the Cheesecake Factory. After a series [...]

After an open house night with grad students, a particularly obsessive grad student named Ramona Nowitzki takes a shine to Sheldon and insinuates herself into his life and work as a girlfriend/assistant. However, Sheldon remains oblivious to her intentions, leaving the gang doubly confounded. She proves to be a positive and helpful influence on his [...]

Leonard is working nights on an experiment – the lasers he needs are only available on the graveyard timeslot – resulting in his inability to drive Sheldon to the university. As a result, Sheldon must find another way to get to work, which includes invoking a favor from Penny on her day off from the [...]

Raj is included in People magazine’s ’30 Under 30 to Watch’ list, sparking jealousy from his friends: Wolowitz received no mention of his mechanical design that led to Raj’s discovery, and Sheldon doesn’t understand why Raj’s stroke of luck (being the first to recognize an already-existing celestial object) is worthy of any recognition. Leonard admonishes [...]

Sheldon becomes distracted from playing Age of Conan by Penny who has accidentally attempted to use her car keys to open her apartment door. Sheldon learns that Penny is frustrated by her failures in life specifically her not getting into any of the parts in plays she’s tried out for, not having sex for six [...]

The guys return from a Renaissance fair (which gives the episode its name) and see Penny with a new guy, Eric, prompting a jealous Leonard to pursue a relationship with fellow physicist Leslie Winkle. All the guys as well as Leslie humiliate Leonard for his apparent failure to keep Penny. Leslie eventually agrees to date [...]