The citizens start to question why the town is still under a quarantine that has cut off medical and building supplies. The citizens find themselves on the verge of a major medical pandemic. Russell and Sheriff Underlay must track down the source of this quickly spreading virus.
Beaver hires Veronica to investigate his stepmother, Kendall, who he believes is cheating on his dad and planning to clean him out, but both are shocked by what they discover. Meanwhile, Wallace begins dating Jackie, against Veronica's advice.
The BAU team travels to San Diego to stop a rapist and murderer who commits his crimes in the middle of the day.
Brooke has an end of the summer party on the beach. As Nathan comes home from basketball camp, Haley tries to tell him how she feels. Elsewhere Lucas deals with Brooke's rules for dating and Peyton deals with family issues.
Hurley struggles with an assigned task inside the hatch as he flashbacks to disturbing memories in his life before the crash. Meanwhile, Sawyer, Michael and Jin learn the identities of their captors on the island. Claire uncovers a startling piece of information about the fate of the raft.
When the school holds a concert in the gym, William accidentally drops a mixing board for the DJ contest. Odd offers to fix it, and tries to get Jeremie to help. Jeremie is busy, so Aelita offers her help. She easily fixes the device, and finds that she is quite talented in using it. The school is holding its finals, as well, and Odd finds that he is not prepared in the least. Meanwhile, Xana possesses Jim and takes Aelita to the factory in order to deliver her to the Scyphozoa.
George wants to get a companion for his depressed mother, but when a rowdy biker (guest star Duane "Dog" Chapman) refuses to give up the stray dog George's mom has grown to love, George takes to impersonating the mayor. Los Angeles Mayor Antonio Villaraigosa guest stars as himself.
After choking on a hamburger and having a near-death experience, Chode tries to make up for the things he has done wrong.
Annabeth must choose between making a case against a kidnapping suspect or saving his victim's life. Annabeth takes a huge gamble when she denies kidnapping suspect, Derrick Adler (guest star Mason Gamble) his right to have a lawyer present during his interrogation in order to force a confession with the hope that he will lead the police to his victim's whereabouts so that she can be brought home alive. Derrick had kidnapped college mate Amy Flynn (guest star Shannon Floyd) after a campus party, a person who he has been stalking for over a year. With time running out Annabeth is put in a tough predicament. Meanwhile, Maureen must decide whether or not to prosecute a detective who obstructed justice in order to protect a fellow cop.
A woman wants surgery to make her look like her when she was younger, to jog her Alzheimer-stricken husband's memory. Christian and Sean work on another Carver victim, who does not have the same physical attributes as the other victims.
When a corpse of a man is found inside a tomb that comes from the Civil War, the team discover that the victim, a Sergeant, was buried alive. During the investigation, Abby tracks down the last phone call of the victim.
When the teenage son of Stabler's old partner comes under suspicion for attacking a classmate, Stabler's inability to treat this like any other case gets him suspended.
When Earl meets a tough biker chick at a Halloween party, it looks like a match made in heaven--but when the costumes come off, the mismatch becomes apparent and Earl takes drastic measures to get out of the relationship. Now, years later, Earl must find a way to make amends for deceiving the girl.
Faced with her first national crisis - the death of nine DEA agents in Latin America - Mackenzie shows strength and resolve in dealing with a corrupt leader. Meanwhile, Nathan Templeton is approached by an ambitious congressman who served with Mac's Vice Presidential candidate, Warren Keaton, and is eager to divulge potentially damaging info in an effort to derail his nomination. Mac's teenage twins resume public school, only this time it's complete with secret service detail and press spectacle, and while popular Horace welcomes the attention, shy Rebecca finds it overwhelming.
Mike visits the San Francisco Zoo and learns what it's like to be a zookeeper, essentially feeding the animals and collecting their poo.Mike then goes to Vermont to a haunted cheese making factory and learns not only how to make cheese, but the art of patience.Finally, Mike learns how to be a volcano ash mud bath mixer (spa technician) in Calistoga, CA and takes a mud bath after a very dirty day. That's not all - Mike also journeys to a live volcano in Hawaii and gets up close and personal with some very hot lava.
Out-of-shape Jim enters a 10K marathon to teach Kyle, who wants to quit basketball, a lesson about not being a quitter -- but he cheats to get first to the finish line.
Byker Grove follows the lives and relationships of a group of young people who are members of a youth club.
The Office is forced into the parking lot for the day when a fire starts in the kitchen. To ease everyone's boredom, Jim suggests a game of "Desert Island" and "Who Would You Do?", where certain staff members reveal a little too much information about themselves. Throughout the day, Michael talks business with Ryan, leaving Dwight feeling left out.