Hal's friend Trey tells him to come to his dental office when he looses a tooth during a poker game, but their friendship becomes in jeopardy when Hal's faced with a $2,000 bill and causes a fight between them. Reese, meanwhile, teaches Lois how to ride a bike, while Malcolm and Dewey find sleeping as their new favorite pastime.

David Sandstrom searches for a drug cocktail to save Audrey Graves, a pregnant woman who has been infected with a new strain of HIV from Africa. In an effort to save her baby, Audrey is induced at just 26 weeks; but it is too late, she has progressed to full blown AIDS and her baby has been exposed to the virus. Carlos attempts to trace the new strain of HIV back to Patient Zero and he encounters many painful memories of his own time in Africa.

Meanwhile, Mayko recruits Simon Jessup, a British neuroscientist, to help her investigate a possible link between IQ spikes and Mad Cow disease. Mayko and Simon begin to develop a personal relationship.

Homer is stoked for a party, where Lenny shows off his new plasma screen HD TV. Three days later and Homer still hasnt left Lennys apartment. Lenny eventually gets him to leave and Marge enters them in a contest where they can win a plasma TV of their own. They dont win, but 3rd place gets them a tour of the FOX studios, where Homer learns about a wife-swapping show where he can win enough money to buy his own plasma TV. Marge agrees to appear and they exchange wives with the Heathbar family. Charles Heathbar winds up falling in love with Marge (who is giving him what he needs), while his real wife Verity finds Homer detestable.

Hank gets sucked into Kahn's get-rich-quick scheme when Kahn buys the car wash that hosts car cruising on Friday nights. But Kahn wrecks the business by trying to cut corners, and gets bought out by Buck Strickland. Meanwhile, Peggy tries to figure out if Nancy is deliberately refusing to take her calls.

Bill gets a new home security system, Nicki throws a birthday party, new neighbours move in, and Margene meets her mother-in-law. Meanwhile, there's a break-in in Bill's hardware store.

When a poison-soaked towel turns up at the station, Lilly re-opens the 1973 case of a murdered female college tennis star.

After hearing gunshots in her apartment building, Jordan investigates and finds a 13-year-old girl standing over her father with a gun in her hand. Jordan is skeptical about the teen's claims to have found him dead, but this all changes after she witnesses two attempts on the young girl's life. Reminded of the loss of her own mother at the hands of a murderer, Jordan is determined to bring this perpetrator to justice.

Meanwhile, Macy, Nigel and Lily investigate a drunk-driving accident and discover that one of the victims is the notorious heir of a prominent family. Yet, none of them are prepared for the shocking secret they discover - a secret the family doesn't want anyone to know.

Susan invites Dr. Ron to meet Karl after he finds out about their arranged marriage. Lynette is surprised that a woman at work is still breastfeeding her child of five. Gabrielle becomes very picky when choosing a birth mother, and a beautiful baby. Bree has to deal with a fresh accusation from Andrew, that of repressed memories.

Peter gets a vasectomy and loses all his sex drive. Lois begins to gain weight, and as a result, Peter's regains his interest in his wife. When Lois' habits get out of control, she has a heart attack. The surgeon must remove Lois' fat to reach her heart, returning her to her normal weight. Meanwhile, Stewie's half-brother Bertram returns to confront him, where they have a war for control over the playground.

Goren and Eames investigate the death of Eric Newsome, an urban explorer who was found in a water tower. During their investigation, they learn Eric had been looking into the files of Dr. Everett Janns, an OB/GYN who had examined his sister's boyfriend's mother years earlier when she had been carrying his sister Lisa.

Wedding plans occupy the girls, and Shane is reunited with her family. Helena pitches in to have Carmen's family flown to Canada, Jenny and Max drift apart, and Kit has stunning news. Peggy Peabody reconnects with her daughter -- but does it last? Finally, Tina has second thoughts about Angelica's custody arrangements, leading Bette to take desperate measures to be with her daughter.

Silvio decides to divide up Paulie's latest score and has to head off a territorial impasse between Vito and Bobby. Christopher turns to his old writing acquaintance, J.T. Dolan for help in a new venture he has planned. Meanwhile, Carmela turns to an unexpected source for help with AJ.

Toby is pressured to reveal the source of the shuttle leak; as election day nears, Santos pushes himself to his limit while on the campaign trial.

Kaiser Chiefs' Ricky Wilson steps in as guest host for more pop-related mayhem. Regulars Phill Jupitus and Bill Bailey test their knowledge of all things musical, assisted by Happy Mondays dancer Bez, Radio One DJ Colin Murray, comedian Jeff Green and Ryan Jarman of the Cribs.