Ian drives a car back to the United Kingdom following his travels overseas unaware there is something hidden in it. With her wedding anniversary just around the corner and a party planned, Mimi becomes even more worried about Paddy's absence.
Alex and her family return from the Hamptons, only to pack and prep for a vacation in St. Barts. Meanwhile, Jill launches an epic redesign of her home; and LuAnn pens a book on etiquette---though Bethenny questions her expertise in such matters. In the dueling diva department, LuAnn and Ramona butt heads. Meanwhile, Bethenny participates in a magazine shoot.
When a pediatrician convicted of abusing patients is found dead, Stabler and Benson investigate and soon find ADA Cabot has a reason for becoming involved in the case.
As they investigate a young woman's death, Murdoch and Dr. Ogden find their relationship threatened when they turn out to be of opposite opinions in the matter of abortion.
House and the team take on the case of Nick, a book editor who loses his inhibitions. The team realizes Nick has frontal lobe disinhibition, which causes him to speak his mind having no control over what he says and making him just like House. Meanwhile, House suspects Wilson and Taub are keeping something from him.
The siege on the White House reaches an explosive end after Jack and Bill work together to try and save President Taylor. Meanwhile, Jonas Hodges makes moves to cover his own tracks, starting with Ryan Burnett.
Chuck, Sarah and Casey learn about a man called “Perseus” who is behind Fulcrum’s plans to build their own Intersect. While Sarah and Casey are sent to find Perseus, Chuck and Agent Cole Barker are forced to stay in a safety bunker. When the mission takes a dangerous turn, their orders to stay out of harm’s way go out the window. Meanwhile, Morgan tries to convince Anna that moving in with him would be a bad idea.
Marshall and Lily are less than thrilled when they hear that Ted's college girlfriend (Laura Prepon) has moved to New York.
Charlie's admission that he's in love with Chelsea gets a surprising reaction from her
Author Richard Castle joins NYC Detective Kate Beckett to help solve the case of a serial killer who is reenacting murders from Castle's novels; Castle becomes very intrigued with the murders and continues to shadow Beckett, much to her chagrin.
RuPaul makes the queens hit the floor in a good old fashioned drag ball inspired by Absolut's real fruit flavored vodkas.
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.
A teenage girl dies at a school friend's party that Grace's niece was at; Grace has a new partner; Johnny tries to learn more about Earl.
When Sylar comes face-to-face with his long lost father, the reunion proves to be what he least expected. Elsewhere, after receiving a tip from "Rebel", Claire must decide if she will help her sworn enemy, Eric Doyle, evade capture. Meanwhile, as "The Hunter" plans to uncover the Petrelli family's secrets and take control of Nathan's operation, Matt finds himself in the spotlight and on the verge of leveling Capitol Hill.
Aaron Stone has to stop Cerebella, whose video is hypnotizing millions of kids.
A horrific apocalyptic dream has Allison shaken, as does the earthquake which follows. Convinced that the end is near, Allison seeks wisdom from a survival guru and purchasing provisions. Meanwhile, Ariel has a crush on a upperclassman who needs help with his geometry class
Kyle risks losing Cassidy's trust when he begins a deception aimed at discovering Latnok's true purpose, and Jessi, devastated by their discovery, has a hard time putting aside her emotions. Elsewhere, Josh plans a perfect farewell for Andy.
The CSIs make a shocking discovery about their murder victim, while Horatio tries to save his son from Julia's erratic behavior.