When Leonard and Sheldon encounter a young woman crying on the curb, Leonard invites her to dinner. She is abrasive, sexy, hard, and sarcastic, but she softens a little when she discovers that the guys aren't trying to get something from her.

يلتقي زميلا الفيزيائيان اللامعان ليونارد وشيلدون جارتهما الجديدة بيني ، التي تبدأ في إظهارهما أنه بقدر ما يعرفان عن العلم ، فإنهما لا يعرفان سوى القليل عن الحياة الفعلية.

يتطوع ليونارد للتوقيع للحصول على حزمة في محاولة لإعطاء انطباع جيد لدى بيني ، ولكن عندما يلجأ إلى شيلدون للحصول على المساعدة ، فإن محاولته في الفروسية تذهب بشكل فظيع.

ليونارد يطلب من امرأة الخروج معه في موعد غرامي لكن يكتشف أن بيني تواعد شخصًا ما.

طرد شيلدون من العمل يجبره على اكتشاف ماذا تقدم له الحياة بعيدا عن الفيزياء، تاركا ليونارد يتخذ قرارات صارمة لأخراج صديقه من حالة الذعر.

خوفًا من أن يضيع وقته على بيني ، ينتهي الامرمع ليونارد لانشاء علاقة مع ليزلي.

تستضيف بيني حفلة عيد الهالوين ، تاركةً ليونارد ، وشيلدون ، وولويتز ، وكوثرابالي في اختبار جديد لمهاراتهم الاجتماعية.

تم تجنيد بيني لملئ فريق هيلو للشباب.

والديً راج يضعانه في موعد غرامي مع فتاة لا يعرفها، ولكن حينما استطاع التحدث إليها أخيرا، تبدي اعجابها بشيلدون.

عندما تمت دعوتهم لحضورمؤتمر في الفيزياء ، يؤدي تردد شيلدون في مشاركة الفضل إلى تشنج بينه وبين ليونارد ، ويؤدي تدخل بيني إلى تفاقم الوضع فقط.

يكذب كل من ليونارد وشيلدون لتجنب رؤية حفل بيني ، لكن شيلدون معقد قليلاً لمصلحته.

مع معرفة أصدقائه بمدى تعامله عندما كان مريضًا - وتجنبه نتيجة لذلك - تم رعاية شيلدون من قبل بيني ، الذي لم يكن لديه أي فكرة عن سبب وجودها.

مع تنرفز شيلدون حول لقاء دينيس ، وهو فيزيائي يبلغ من العمر 15 عامًا وأذكى منه ، يساعده ليونارد في البحث عن طريقة لفضح أبحاث دينيس.

يجد شيلدون نفسه مطرودا من عصابة فريق فيزيكس باول واستبدله بـ ليزلي، لذلك شكل فريقه الخاص ، على أمل إثبات أنه متفوق.

عندما يؤدي تسليم مجموعة أخرى إلى انتقاد بيني في ليونارد ، قرر أن الوقت قد حان للتخلي عن عادته ، كثيرًا لاحتجاج أصدقائه.

تقع بقية المجموعة على شقيقة شيلدون التوأم ، وتعطلت خطة ليونارد للفوز بقلبها عندما يعلن شيلدون أنه سيكون الشخص الذي سيقرر من يمكنه مواعدتها.

تريد بيني إقامة حفل مفاجئ مع ليونارد ، لكن تساهل شيلدون في متجر إلكترونيات يطردها خارج المسار الصحيح.

انفصال بيني يدفع ليونارد إلى استدعاء الشجاعة ليطلب منها الخروج في موعد غرامي ، ويذهب كل منهم إلى شيلدون للحصول على المشورة في الموعد القادم.

Penny's first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant.

A jealous Leonard reacts to Penny's new guy by rebounding with Leslie.

Sheldon creates a monster when he introduces Penny to online gaming.

Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.

Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.

Sheldon and the gang are confused when a young grad student is attracted to him.

When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate.

Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.

Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.

Leonard asks Penny for advice when his new relationship starts moving too fast.

Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.

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.

Sheldon creates a scientific procedure for making friends.

Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.

Leonard and Penny are drawn together after a disastrous visit from Leonard's mother.

A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz.

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.

Penny's home business turns into a complete nightmare when Sheldon takes over.

Penny squares off with a new beautiful female neighbor who may become the building's "new Penny."

A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night.

Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and must stay with Penny.

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.

The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.

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 Leonard's hope for some romantic time with Penny and the guys' friendship with Sheldon.

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.

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

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.

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.

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

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

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

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

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.

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 with Penny.

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.

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

Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with 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 winds up in traffic court when he gets a ticket because of Penny.

When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

Leonard and Sheldon compete for the attention of a famous female physicist.

Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.

While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm.

Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.

The guys are concerned as Sheldon searches for an alternative to human companionship.

An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.

Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his.

Leonard keeps an affair a secret from Sheldon, Howard and Raj.

Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.

While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.

Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.

Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.

The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.

Leonard's idea for a smartphone app derails his friendship with Sheldon.

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend's girlfriend.

A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.

As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.

Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.

Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.

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 discuss how Penny groomed Leonard to be willing to try various things and more adventurous boyfriend... for some other woman — Priya.

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.

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 her skills as a lawyer to nullify the charges due to the agreement's vague wording, much to Sheldon's dismay. When the guys take advantage of Priya's skills in order to eat Greek food on pizza night, Sheldon goes to Penny, who invites him to a girls' night out with Amy and Bernadette, which Sheldon agrees to after Penny mentions that they may be talking trash about Priya. After the girls drink some cocktails, they decide to take Sheldon dancing, which Sheldon reluctantly goes along with. After dancing, Sheldon takes an intoxicated Amy back to her apartment and as well as talking about Priya, meets a monkey who is addicted to smoking cigarettes. Amy tells Sheldon not to give in to Priya's law skills, before kissing him and going to her bathroom to vomit.

Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.

When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.

When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.

Penny is worried with how damaged her friendship with the guys will be in the aftermath of her sleeping with Raj while Sheldon becomes the leader of the paintball team.

A fight between Sheldon and Penny leaves Amy caught in the middle, while Leonard tries to spice up his long-distance relationship with Priya.

Leonard and Amy get to know each other better, while Howard and Bernadette spend the weekend with Mrs. Wolowitz.

Penny plays Matchmaker for Raj, which results in him finding a girl he is comfortable talking to.

Sheldon and Leonard get invited to a party at Wil Wheaton's house, and Howard gets an out-of-this-world opportunity.

Sheldon's mother, Mary Cooper, comes to visit, but Sheldon is annoyed that she also spends time with the rest of the gang, instead of catering to his every demand.

A cute comic book artist puts Leonard and Priya’s relationship to the test, while Sheldon tries to scare the guys for Halloween.

Amy becomes heartbroken when she discovers that Penny and Bernadette went wedding dress shopping without her.

Leonard and Penny try hanging out as friends on a 'non-date', but end up purposely ruining each others chances with perspective dates. Meanwhile, Sheldon enlists the help of Bernadette and Amy to overcome his fear of birds.

When Stuart asks Amy out on a date, Sheldon must confront his feelings and consider where his relationship with Amy is going.

Leonard must face his fears after being contacted by his high school tormentor.

Sheldon gets in trouble with Amy when he isn't impressed by her recent accomplishment, and Howard must come to grips with Bernadette's dislike of children.

Leonard, who broke up with Priya, asks Penny out to a spur-of the-moment romantic dinner for two, and the duo contemplates on their relationship.

Leonard and Penny deal with the idea of starting a relationship again and Raj finally finds a "woman" he can talk to without being drunk, in the form of Siri on his new phone. Meanwhile, Sheldon decides to start a YouTube series entitled "Sheldon Cooper presents Fun with Flags" with the help of Amy.

Sheldon's selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname.

When Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab.

Sheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy.

Sheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to go into space. Penny beats Leonard in chess, the first time she plays.

Sheldon must choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.

Penny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock. Meanwhile, Raj decides he has met the “Future Mrs. Koothrappali” after his parents set him up on a date.

Celebrating the 100th episode of US sitcom The Big Bang Theory, Rick Edwards travels to the Hollywood set for an access-all-areas visit, catching up with the cast and learning everything there is to know about the show.

This behind-the-scenes special takes fans through everything from the writing of the script to the recording of the show in front of a live audience.

Celebrating the 100th episode of The Big Bang Theory, Rick Edwards looks back at some of the US sitcom's most hilarious and memorable scenes and talks with the cast and crew on the set in Hollywood.

The actors share their favourite moments and reveal a few secrets about the making of the show.

When Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero.

After the guys throw Howard a bachelor party, Bernadette reconsiders marrying him after learning about his sexual history.

When NASA moves up Howard's mission, he must face his fears and Bernadette's dad, thus putting the wedding plans in jeopardy. Meanwhile, Leonard says something surprising to Penny in the bedroom.

The fifth season ends with Howard and Bernadette deciding to get married before his NASA mission, causing the gang to scurry into overdrive in an effort to stage the wedding. NASA astronaut Mike Massimino has a cameo as himself.