A mysterious illness that baby Aaron suddenly contracts sends a desperate Claire, Kate and French woman Danielle to return to the same area where Claire was initially kidnapped. It is there where she believes she can find a cure for Aaron's illness. In the meantime, Jack and Locke are doing their best to keep their prisoner a secret from the rest of the survivors on the island.
Rory dazzles the crowd at a journalism panel, but the next day, she's devastated to learn how her boyfriend behaved during their breakup.
Sam has a reunion with a girl he once met, Meg, but it turns out that she is using the brothers to lure their father John to his doom.
Kavanaugh seeks the help of Antwon Mitchell in his ongoing quest to take down the Strike Team. In the midst of this, Kavanaugh has a lot on his mind as his ex-wife reenters the picture, and he reluctantly agrees to let Vic send Emolia undercover to infiltrate a Salvadoran gang that is stockpiling grenades.
When an ambulance explodes while carrying the remains of a Marine's body that was killed in a car crash, the NCIS team are called in to investigate what actually happened. The investigation leads them to some sudden discoveries - the DNA of the victim found in the ambulance doesn't match the Marine's DNA, the ambulance was set up to explode, and the family of the dead Marine is hiding a very important secret.
Jim gets mad when he finds out that his neighbor Julie has been writing children books and basing them about him.
J.D. is still dealing with his recent breakup and trying not to kill intern Keith, who has become annoyingly perfect. To make matters worse, a favorite patient is in a serious coma and each of the staff finds their own way to deal with it. Dr. Cox and the Janitor bond over drinks at the bar and Carla makes it her mission to make the hospital's gym female friendly. Meanwhile Turk suggests, that J.D. and Elliot find themselves 'booty calls'.
Dr. Kelso is outraged, when he discovers, that a bird has been living in Sacred Heart. He orders the Janitor to dispose of it immediately. However, the Janitor likes the bird so much, he secretly keeps it as a pet. Meanwhile, J.D., annoyed with Keith, tries to get his intern fired, but things don't turn out as intended.
Shirley, Paul and Brad batten down the hatches as Bev files for divorce hours after her marriage to Denny, and demands half of his assets. Alan helps defend an old friend who was fired for smoking on her private time.
Doug Waverly and Nick Pratt are charged with rape and murder in the disappearance of Canadian student Jennifer Durning after Nick's cousin, Jason King, claims that while he had consensual sex with her that night the other two raped her. A stray pubic hair leads Novak to Keith Willis, a drunk who was paid off by the boys to get Jennifer out of the hotel and who later saw the boys kidnap her, but Willis exactly fit to be a witness as his mind has gone after years of alcohol abuse. Jason King disappears. Although they are able to find a bug in Donnelly's office, they are not able to prove that it was placed there by Pratt or Waverly. Judge Donnelly is forced to dismiss the case against the two boys since there is no case without Jason's testimony.
Alexx’s DNA is found throughout her neighborhood where she is suspected to be responsible for the death of a convicted child molester. The CSI team soon learns that mindset of the neighborhood could lead to any of community wanting the man gone. The team must find out who the real killer was to clear Alexx.
A sportscaster becomes a full-time dad when his ex-wife decides to accept a job out of the country and his teenage daughter, Breanna, moves in with him.
Spencer continues to shower Naomi with affection after she reveals her HIV-positive status. However, her newfound confidence prompts her to dump him and seek to profess her love for another man. Mona tries to comfort Spencer, but he rejects her for failing to back him throughout the relationship. Dee Dee agrees to join her new actor boyfriend in a reality show, and winds up humiliated. Charles is surprisingly supportive when Big Dee Dee is asked to do a nude scene in her film debut.
Joan and Toni fight when Toni claims Joan's good fortune has made her a bad friend. Williams learns how to play video games.
Emma's downward spiral into the world of eating disorders could have dire consequences on her. Meanwhile Alex and Hazel try to play nice for Paige.
Karen gets stuck in the middle when Brent and Lacey fight it out to see who is the best at getting people to open up to them. Both Wanda's credit rating and her ego take a beating when she's denied a credit card that Hank is approved for. Oscar helps Davis get into shape, but Oscar's standards, like much else in his life, are somewhat out of date.
Kris gets the chance of a lifetime, and soon finds that fame is taking over. She wonders if she's going to be able to keep her old friends, with all the forces pulling her away. Meanwhile, Rebecca gives Matt a helping hand.
Annie and Ruthie spend the day together to unwind, while Lucy's world becomes complicated by both professional and personal news, and Eric unintentionally shakes up things between Rose and Simon.
Logan wrestles with his conscience when he learns that Martha is riding in the motorcade with the Suvarovs. Audrey convinces Curtis to take action as Lynn continues to abuse his authority. Jack learns that an ex CTU agent, Christopher Henderson, works for a company which is connected with the nerve gas.