Sherlock assists with a double homicide that has the same M.O. as a series of murders that took place 13 years ago. Meanwhile, after being frozen out by Sherlock, Watson visits his old rehab center in order to learn more about the mysterious man in her care.

The McKinley High production of "Grease" opens, and Santana returns to help out. Rachel has another run-in with Cassandra, her dance instructor; and Kurt and Rachel visit Lima. Finn becomes the interim Glee Club Director.

As the doctors continue with their lawsuit, they’re forced to confront the realities of their injuries. Meanwhile, Bailey tricks Arizona into helping her with a pediatric case, and Cristina tries to find normalcy in her new environment.

Mac, Charlie and Dee struggle with their faith as Charlie's mom fights cancer. Meanwhile, Frank loses his memory amidst a search for buried treasure.

From "New Girl," actress Zooey Deschanel; comic Lisa Lampanelli; musical guest Donald Fagen

Leslie gets upset when April tries to get Lot 48 made into a dog park. Tom enlists Ben’s help as he tries to launch his new business venture. Andy hones his crime-scene investigation skills.

A resourceful third party raises the stakes as Finch and Reese try to protect their latest person of interest, a brilliant surgeon.

Olivia receives an anonymous letter containing a coded warning which could expose Huck's dark past. Meanwhile another Pope & Associates secret has already been exposed and Olivia asks Harrison to step up and handle it. And in the White House, Cyrus and Fitz are dealing with the ramifications of Cyrus' husband's first front page news story.

Raj and Howard try to to figure out why Sheldon disappears at 2:45 every afternoon; jealousy arises in Penny and Leonard's relationship.

Campbell's promotes soups for millennials, the Petraeus scandal escalates, meth protects against influenza, and Chris Stringer talks primitive humans.

From "New Girl", actor Max Greenfield; from "Ben and Kate", actress Lucy Punch.

Andre's plan to take the guys tailgating is thwarted when their high school nemesis Frank "The Body" Gibiatti and his gang have the same idea. Taco tries to sell knockoff merchandise and has a run in with Chicago Great Jim McMahon.

The women of the office try to teach Dwight how to interact with female clients. Angela suspects the senator of cheating. Toby convinces some of the guys to grow mustaches.

Terrifying hallucinations leave Elena shaken and confused, causing her to make a dangerous mistake. After giving Stefan some very disturbing news about Elena, Klaus takes matters into his own hands. Professor Shane reveals a story of ancient witchcraft to Damon and Bonnie. With help from Klaus and Stefan, Jeremy begins a new chapter in his life. Finally, Elena makes a painful personal confession to Stefan, and Matt gives Damon startling new information about Professor Shane.