Jack is nearly delirious from lack of sleep and struggles to overcome the haunting events that brought him to Australia and, subsequently, to the island. Meanwhile, Boone gets caught in a treacherous riptide trying to save a woman who went out swimming. A pregnant Claire's health takes a bad turn from lack of fluids, and a thief may have stolen the last bottles of water. Veronica Hamel guest-stars as Jack's mother, Margo. Also, Jack flashes back at 12 years old, to find himself on the playground in an altercation with a bully, who ultimately beats him up, and later learns a life lesson from his father.
Jonathan's wallet is stolen by a super-speed thief, Bart Allen, who is faster then Clark. Bart comes to the farm and becomes friends with Clark, but Bart returns to crime when he sees an ancient manuscript that Lex has. As Clark soon realizes, the manuscript holds a map to one of the kryptonian crystals and he must go up against Bart to recover it.
After Gina keeps complaining about her current workplace, Joey decides to loan her some money, so that she can open her own salon, but she has second thoughts. Also, Alex's husband Eric returns to town and things get weird between him and Joey.
A body of a woman in the Navy uniform is found by two sailors. Ducky links the murder to an unsolved case from 10 years ago, and the team is searching for the serial killer who leaves the note promising to return.
In the aftermath of the school shooting everybody is talking as they need to get some closure over what happened, but Sean who thinks he has everything under control may not be as well adjusted as he though and may have to take a trip back home to confront his past. Meanwhile JT and Danny have shun Toby out for making friends with the school shooter plus Toby is planning on going to Rick's funeral.
Cheryl and Dana are forced to smash their way out of a locked garage, because they ignored Jim's lesson on how to open the door from the inside.
The entire squad races against the clock to solve the puzzles and uncover the clues scattered throughout the city by a serial killer who is taunting them to find him and the next victims on his list.
The detectives investigate the death of a phone-sex operator and the kidnapping of a wealthy man's son; and Clark's tryst with a murder suspect is used to derail the prosecutor's case.
When Carmen's school refuses to let her back in, the recently laid-off Angie agrees to home school her. But the money cut also forces a postponement of George and Angie's wedding.
Davis regains his sense of smell in a freak but fortuitous accident. It's a beautiful new world, until the smell of his fellow officer proves too much. Meanwhile Brent realizes just how little he knows about his fellow Dog Riverites and scrabble champ Lacey is challenged by an unlikely some would say inarticulate wordsmith.
Byker Grove follows the lives and relationships of a group of young people who are members of a youth club.
In an effort to help Wallace's new crush Georgia, who was duped out of her money in an internet scheme, Veronica must outwit a group of computer "thugs," known as the Silicon Mafia. Meanwhile, Keith makes Veronica introduce him to her new boyfriend Troy before allowing her to go to the homecoming dance with him. Later, Logan helps Duncan edit together a memorial video for a school dedication ceremony marking the one-year anniversary of Lilly's death. The dance and the video bring back Veronica's memories of when the four of them were friends.
When an overwhelmed Jr. thinks he is not smart enough to take care of his own son, Michael tells Jr. that ""Jr., Jr."" is a ""magic baby,"" and that every time he holds him, it will make Jr. smarter. The ploy works, but in the process Jr. becomes somewhat arrogant with his new-found knowledge, so Michael brings Franklin in so that the two geniuses can match wits. Meanwhile, Kady catches Claire sneaking back into her bedroom after hours and threatens to tell their parents, unless Claire does some favors for her.
Wanting to smooth over her relationship with Dean, Lorelai suggests a night out with Luke and Rory – but the evening goes awry.
Vicky Pollard is caught hiding mix n' match candy in her pants at a supermarket. Dafydd comes out to his parents, but his mother's reaction is not quite what he expects. Emily has a new companion, a novice transvestite with a moustache. Marjorie Dawes advises one of her Fat Fighters to "waddle back to your seat". At the local spa, Bubbles offers to pay her huge bills in an inappropriate manner. Maggie and Judy's stomachs turn on learning the jam at the village fete was made by a lesbian.
When J.D. finds Dan with Elliot, Turk tells him to use the hurt brother excuse to get them to break up, just like Turk uses his diabetes to get stuff from Carla. But then J.D. realizes he wasn't hurt at all... Dr. Cox and Dr. Kelso unite to try and torment their common enemy: Dr. Clock.
Felix organizes a "dare night" to test the limits of his new classmates. While out playing the game, Lucas meets a mysterious new girl, Anna, and the two of them seem to hit it off. Peyton tearfully confesses to the church that she recently tried cocaine and Keith is caught off guard when a beautiful woman comes to the shop and begins flirting with him. Meanwhile, Karen goes on a date with Andy, her younger professor.
An 18-year-old girl is stabbed to death in a bathroom of a popular Miami nightclub. Horatio learns that the victim was an investigative aide working for Alcohol Beverage Control and was monitoring underage drinking. As Horatio interviews the club's owner, an unknown man drives by the club, sees that the police are there, and crashes his car while fleeing the scene. However, the case gets more complicated when they discover another murdered victim inside the car. DNA from the second victim's watch ultimately leads them to a day spa where the services may not be entirely legal. Meanwhile, Calleigh and Ryan work together to determine whether an insecure and underage teenager at the club that night had anything to do with the murder.
Harry reawakens sleeper agent Fred Roberts, a renowned chemist and family man. As Fred becomes more deeply involved with deadly terrorists, Tom has a crisis of conscience which could jeopardise his career.
Mona must work long hours as she prepares a major presentation for Kai about her talent search idea. She begins to lose touch with her family and friends, as she misses out on Dee Dee's weekly parties and is unaware of major news like Spencer getting a new girlfriend and Phyllis and Ray deciding to live together. Mona makes an effort to better balance her personal and professional lives, with disastrous results. Meanwhile, Adam, upset that being gay is no longer the ""in"" thing, decides that he is going to be straight.