While investigating an explosion that kills two people, Sherlock discovers a crime that’s been lying dormant for years. Meanwhile, Watson encourages Sherlock to finally pick a sponsor.

It's time for sectionals, and New Directions receives guidance from some of the recent McKinley graduates who volunteer to mentor the glee club during their Thanksgiving break. Meanwhile, Rachel and Kurt have a non-traditional holiday dinner in the Big Apple.

Cristina and Owen continue to figure out their relationship amidst the pending lawsuit; and Bailey argues with Ben over plans for their upcoming nuptials. Meanwhile, Callie recruits Jackson to help find a solution to Derek's hand, but he is preoccupied by a shocking situation with April.

With Charlie under his wing, Frank cleans up so he can get his hands dirty and help out his old company with one last big merger. An unwritten rule of the bar gets the rest of the gang caught up in a case of mistaken identity.

Leslie is suspicious about a new park design from an Eagleton architect. Tom asks the office for help with his new business. Andy tries to make his job as a security guard exciting.

The team faces a challenge when the numbers of both a man and his wife come up in the machine.

Harrison leads the team in managing a billionaire businessman who seems to have lost his sanity; meanwhile, Olivia and the White House prepare to celebrate the President's 50th birthday, as James continues to investigate Cytron and discovers something that could change the fate of the country.

Sheldon and Wolowitz's fight over a parking spot at the university impacts the whole gang.

America foregoes a nuclear moon missile, Boeing blocks pension benefits to gay couples, Stephen pushes "America Again," and Sean Carroll explains the Higgs field.

Actress Kristin Davis; from "Ben and Kate", actor Nat Faxon.

Pete fights over a pair of shoes with a man in a wheelchair. Taco teaches a dog to recognize the scent of sex. Jenny and Kevin get Ellie a piano.

Angela goes to Dwight for help when she learns that her husband is having an affair. Stanley and Phyllis take advantage of Jim when he needs a favor, and Pete distracts Pam as she begins painting her mural.

Caroline does her best to be there for Stefan and Elena in a tough time. Damon tries to convince Stefan to help him uncover Prof. Shane’s motives, but Stefan is intent on carrying out a different plan with Klaus. At the annual Miss Mystic Falls Pageant, Elena and Caroline give April advice on which dress to wear, while Tyler and Hayley work together on a secret project, and Damon confronts Prof. Shane with his suspicions. Alarmed by the vivid nightmares he’s having, Jeremy turns to Matt for help, but the situation escalates sooner than anyone expected.