The Big Bang Theory

Sheldon and Amy’s honeymoon runs aground in New York in the twelfth season premiere. Meanwhile, Leonard and Penny discover they’re uncomfortably similar to Amy’s parents.

Sheldon and Amy drive themselves crazy trying to figure out what 'perfect gift' Leonard and Penny gave them for their wedding. Raj decides he wants to settle down and asks his father to arrange a marriage for him.

Howard's life gets complicated when Stuart starts bringing his new girlfriend home. Penny and Leonard talk about starting a family while Raj explores an arranged marriage.

Sheldon won't tell anyone why he's never mentioned Tam, his childhood best friend, so Leonard takes matters into his own hands. Bernadette and Penny take out Raj's fiance, Anu, for dinner to get the skinny on her.

Amy doesn't have time to work on a project, so Sheldon goes to great lengths to ensure she can work with him even if it means sabotaging her career in the process. Raj doesn't want Howard to join him in hosting a show at the planetarium.

When Howard dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny's Halloween Party. Leonard is shocked that Penny doesn't remember their first kiss.

Leonard is caught between a rock and a hard place when he's responsible for distributing extra grant money. Bernadette turns the backyard playhouse into a hideaway from her husband and kids.

Sheldon tries to bond with Amy's father, but when Howard lures Mr Fowler away with magic tricks, Sheldon has no choice but to bond with Mrs Fowler. Raj and Anu try to get physical for the first time.

Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been discovered and disproven. Also, ultra-competitive Bernadette asks Stuart's girlfriend, Denise (Lauren Lapkus), to teach her how to beat Howard in a popular videogame.

Sheldon and Amy are still down about their theory being disproven, but a VHS tape from Sheldon's past inspires him to not give up. Also, Bernadette turns into a pageant mom when she tries to help Howard ace his Magic Castle audition. Special guest stars include Young Sheldon's IAIN ARMITAGE, LANCE BARBER and MONTANA JORDAN. CHRISTINE BARANSKI returns as Leonard's mother, Beverly.

Penny and Leonard organize a paintball game that results in mayhem, when Sheldon is jealous of Amy, Raj catches Anu with her ex-boyfriend, and Stuart doesn't want to move in with Denise.

Penny's ex-boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard to help. Raj attempts to mend things with his ex-fiancée, Anu.

When Sheldon and Amy's Super Asymmetry Theory is proven by two physicists from Chicago, they're thrilled - until they try to kick Amy off their Nobel Prize nomination! Meanwhile, Bernadette has a big success at work and Penny's going to be a part of it…whether she wants to or not.

Sheldon is thrilled to help Bernadette and Howard navigate bureaucratic paperwork, until he discovers they are breaking the law. Leonard is disappointed when his friends exclude him from a scientific project.

Penny tries to seduce an abstaining Leonard to ruin his 'donation' for her ex-boyfriend, Zack, and his wife, Marissa. Howard, Bernadette, Anu and Raj turn Raj's cancelled bachelor party into a couple's trip aboard the 'vomit comet.'

The gang finds out Wil Wheaton hosts a celebrity Dungeons and Dragons game involving William Shatner, Joe Manganiello, Kareem Abdul-Jabbar and Kevin Smith. Deception and betrayal are the path to make it to the one open seat.

Penny and Bernadette go to San Diego for a pharmaceutical sales convention, leaving Howard in charge of the kids. Sheldon finds a book on experimenting on kids, and the guys plus Amy make a day of it.

Pemberton and Campbell charm America on a publicity tour, so Sheldon and Amy bring Nobel laureates Kip Thorne, George Smoot and Frances Arnold to their side. Halley's fear of the dark leads to conflict for Howard, Bernadette and Stuart.

Contemplating what it would mean to all women if she were to win a Nobel Prize causes Amy to have a meltdown. Koothrappali and Wolowitz try to relive the good old days after Wolowitz buys a scooter that looks like the one he had years ago.

Raj is worried people won't take him seriously in his own field after publishing a paper that suggests he may have discovered alien life. Leonard wants to be the principal investigator on a plasma physics study.

Kripke has proof that Dr Pemberton plagiarised his thesis, and Sheldon and Amy aren't sure whether they should turn him in or not. Howard is surprised to learn that Bernie wasn't the only waitress at the Cheesecake Factory who had a crush on him.

Leonard is pleasantly surprised when his mother, Beverly, comes to visit and she's genuinely kind toward him - until he finds out the real reason why she's there; Meanwhile, Denise and Stuart overstay their welcome at the Wolowitz house.

Amy and Sheldon wait for the news. Howard and Bernadette leave their kids. Leonard and Penny keep a secret.

Bernadette and Howard leave their kids for the first time, Penny and Leonard try to keep a secret, Sheldon and Amy stick together, and Raj makes a new friend as the gang travels together into an uncharted future.