Rex and Noah enter the Zoo. A restricted area on the base. Some personal secrets are revealed.
Lt. Tamara Johansen tries to track down what is causing the crew to hallucinate.
An elderly patient admitted into the E.R. for a heart condition sees a familiar face, a long lost love who happens to be in the E.R. as well for a fractured arm, and the staff find themselves caught up in their love story. Meanwhile, Karev treats a troubled teenage patient (guest star Demi Lovato) whose parents brought her in for schizophrenia, and Meredith can't help but tell Cristina about her suspicions of Owen -- which inevitably messes with Cristina's head.
Maya and her unborn baby are fighting for their lives on the operating table, and Addison, Amelia and Fife try everything humanly possible to save them. Meanwhile, Sam operates on an incoming crash victim and later makes a grim discovery; Cooper makes an ill-timed but valiant effort with Charlotte, and the staff’s world gets rocked by an unexpected death.
Reef, Broseph and Johnny list the hotel as a "clothing optional" resort with unexpected results. The girls decide to have an all-girls party in one of the suites, but Lo starts to believe that their night will be ruined when her mom joins the party. Meanwhile, Johnny becomes traumatized after seeing two male hotel guests doing naked yoga and Reef and Broseph try to snap him out of it.
Mark continues his interrogation of Hellinger in a desperate attempt to find out when the next blackout will occur. Demetri must choose between helping Janis and Simon break into NLAP to stop the blackout from occurring, or turning the fugitive Simon in to the FBI. Elsewhere, Lloyd finds the common denominator that can help him solve the complex equation he was working on in his flashforward.
Leslie is disappointed when her new park plans are put on hold by a visit from two state auditors. April has plans for Andy at her birthday party, and Ann tries to piece together a romantic mystery.
Founder's Day has finally arrived, and everyone is busy with last-minute preparations for floats and fireworks. Stefan is uncomfortable with Damon's new attitude toward Elena, but Elena is more concerned about repairing her relationship with Jeremy. Jeremy is worried about Anna, but not sure he's on board with her latest plan for the future. While Caroline is enjoying her day as Queen of the celebration, she also tries to help Matt and Tyler get their friendship back on track. Finally, although Damon and Alaric do their best to stop him, Johnathan Gilbert sets a plan in motion that brings Founder's Day to an end amid chaos, destruction and death.
A series of shocking surprises await the crew when they discover a secret community living on a tropical island. Robert risks his life to save Bomber during a gunfight with drug runners, and Mike investigates claims of an illicit romance between two crew members.
On the eve of an important final exam in Spanish, everyone's grades are jeopardized when it is discovered that Señor Chang has a damaging secret.
Romantic sparks begin to fly when Patrick Jane and supposed psychic Kristina Frye cross paths again during the CBI investigation into the murder of a charismatic head of a non-profit organization that fights human trafficking.
When Walter discovers that Peter has traveled to the alternate universe, he and Olivia gather three cortexiphan children with the ability to transition safely between the two Earths.
The final six get the chance to earn time with their loved ones in a fiercely fought reward challenge. Desperate for options, the remaining heroes make an unexpected ally, hoping to turn the game around.
The showdown between good and evil is at hand. With the Apocalypse looming, Sam and Dean realize they are out of options and make heart-breaking decisions that will change their lives forever. A beloved character faces death.
Michael is surprisingly cheerful after learning some bad news about Donna. The new parents, Pam and Jim, have trouble staying awake in the office. Meanwhile, Angela takes matters into her own hands when Dwight refuses to honor their contract.
Michael is surprisingly cheerful after learning some bad news about Donna. The new parents, Pam and Jim, have trouble staying awake in the office. Meanwhile, Angela takes matters into her own hands when Dwight refuses to honor their contract.
The trial of The Gravedigger hits close to home for members of the team, and everyone at the Jeffersonian must work overtime to uncover the forensic evidence to elicit a conviction.
Semi-final battles at the Grand Festival. With Nando vs Zoey. Then Dawn vs Jessilina.
The ladies bask in some fun in the sun when Ramona organizes a "renewal getaway." Still stung from her loss, Bethenny is comforted by the ladies---until Kelly kicks up some drama. Meanwhile, LuAnn tunes up in the Big Apple by recording a song in the studio.