Rodney McKay goes in search of his sister on Earth after she is kidnapped by the head of a powerful corporation.
While in Chicago Mac uncovers more clues about his stalker and reveals his troubled past. Meanwhile, in New York the rest of the team is in danger. The hunt is on to figure out the identity of the 333 stalker before time runs out.
The Hells Angels are the most powerful and well-known biker club on the planet, boasting over 2500 members worldwide. In April 2002, a riot in a Nevada casino between the Hells Angels and their rivals, the Mongols, kills three gang members and creates headlines around the country. Federal authorities seize the opportunity and send a team of undercover agents to infiltrate the outlaw biker group. Along the way, they uncover a world of sex, rampant drug use, and vicious violence - employed to ensure the Hells Angel's place at the top of the biker world.
Dan invites Serena and her family to spend the holiday with his family, creating an uncomfortable situation for Rufus and Lily. The children are unaware of their complicated romantic past. Meanwhile, Blair's freaks out when she learns that her father isn't coming home for Thanksgiving. Nate spends the holiday with his family, but their awkward dinner quickly goes from bad to worse.
Emerson, Ned and Chuck investigate the death of Tony DiNapoli, who appears to have been strangled by a woman. Meanwhile, business at the Pie Hole plummets when a new candy store opens in town. Alfredo Aldarisio returns and continues to pursue an oblivious Olive who, herself, still pines for affection from the Pie Maker.
While investigating the case of a murdered homeless girl, Reese and Crews stumble across a child who was kidnapped when he was three.
The BAU and local authorities in Los Angeles investigate gang-related serial killings that might possibly involve a famous comic book artist.
This flashback episode reveals secrets about Dutch (Nick's father) and the relationships he had with Nick, Tripp, and Letitia. Karen's intimate view towards Nick is put on hold as she takes a liking to Simon Elder. Brian's attempt to get his son takes a turn he didn't expect and Jeremy continues to hide how much he is worth from Sofia.
Nikki starts admiring and complimenting with the customers at the Khaki Barn so she can earn more money to buy Jonesy new skates, but when she accidentally calls Jonesy on the one of the new cell phones Caitlin gave all of them, he overhears her flirting with one of the customers and thinks she's cheating on him. Meanwhile, Jen gets stuck in a question booth, and Wyatt lets the gang endlessly prank him so he can finish his new album from humiliation. (The title of the episode refers to Oops, I Did It Again, a single by Britney Spears.)
When Clover reads about the opening of a brand new underwater hotel off the coast of Malibu, she's totally psyched. Only when she tries to make a reservation, she's told that it's for VIPs only. Unless she's a movie star, pop singer or celebutante, she isn't welcome. Meanwhile, Jerry informs the girls (Sam, Clover, Alex and Britney) that water levels around the Earth are on the rise. He sends them to check it out. In a b-story, Alex gets over her jealousy of Britney.
Jaime goes on a vacation with Becca at a spa resort, but things go awry when she's pulled into a deadly game with another guest at the resort.
The designers are asked to create a menswear outfit for Tiki Barber to wear on The Today Show. They have $150 and two days to complete their looks.
Angelica's teacher is having a baby so she brings in a hot handsome substitute teacher that Angelica falls in love with. She tries to date him by failing her assignments. Meanwhile, Tommy, Phil, and Chuckie are part of the tennis club run by Pangborn. Chuckie is trying to avoid showering at the boys' locker room, but when he takes the chance, he realizes he has nothing to worry about.
When a comic book starring Chuckie's favorite superhero Armadillo Dave gets cancelled, he becomes too depressed to help Tommy with his science fair project. Tommy has to buy a rat for his project, but the last rat available is a mean one. It scares everybody. Kimi made Tommy a simple one lane track for his rat, much to his disappointment as he feels he would get a failing grade for it, but needs Chuckie so he can get a good grade on it since Chuckie has done it before. The gang tries to find Chuckie a new hero to worship.
While trying to track down a delusional and violent Marine who thinks he's still in Iraq, the NCIS team will learn that the man has been the subject of a secret experiment - and it comes with a high price to pay.
Booth and Brennan investigate a mall Santa named Kris Kringle who was found dead by two elves. A series of clues makes the murdered mall Santa seem like he's the real deal.
When the paternity of a missing young boy is placed into question, Stabler wonders if he really is the father of Kathy's child. Later, Stabler faces the possibility of losing not only his partner but also Kathy and the baby when she and Benson are in an accident.