A peaceful day of exploration turns deadly when a sudden explosion traps Marguerite and Roxton in an underground chamber. Their only hope for escape is Challenger, but the same explosion has left him with no memory of who he is, or what has happened to his friends. Meanwhile, a contest of friendly rivalry between Veronica and Finn leads to an enigmatic discovery at the Treehouse, as another memory from Veronica's childhood is literally uncovered. Faced with certain death, Roxton and Marguerite reveal emotions best left buried, so that even if they do survive their ordeal, there's a chance their relationship will not.
Rescuers find the body of Alex's father, and he is given a hero's burial; Faith and Bosco tail a convicted rapist released on appeal, certain that he will rape again; dissatisfied by Tatiana's explanation of her whereabouts the eight weeks she was missing, Sully investigates further and uncovers some astonishing and heartbreaking facts about his wife; after Chevchenko threatens to kill him if he doesn't roll over on Faith and Sully, Frankie tells Swersky that the raid on Chevchenko's numbers business was a hummer bust, leading Chevchenko to threaten a lawsuit and have another angry confrontation with Sully.
A Mother's Day get-together at Stevie's is disrupted when the IRS evicts the Van Lowes from their home. Sophia: Shannon Tweed. Olivia: Sommore. Sheriff: Geno Kirkland. Stevie: Jenna Von Oy. T: Ken L. Nikki: Mo'Nique.
Dar receives three hidden signals, indicating that the final challenge of his quest is about to begin.
Maya is stunned to learn that her mother has decided to sell her house and move away with her boyfriend. Toni's mother surprises her by coming to town for Joan's Mother's Day brunch. William eagerly anticipates a visit from his mother, who comes bearing a cake from his aunt's award-winning recipe.
Angel pursues Connor, who makes a new friend on the streets; something else comes through the portal from Quor-toth; Lilah approaches Wesley.
The Colonel drops by to tell Ruthie about the death of a soldier she has been corresponding with. Ruthie shares her letters with the family. At the memorial service, Eric asks everyone to advocate good deeds and go out into the community, as the family does.
Elaine auditions for "A Chorus Line", but doesn't get a call back. She accidentally bumps into the casting director, whom she finds attractive and nice. They go out for dinner and end up having sex. The next morning at work Elaine feels horrible for not giving her full self at the audition and Nelle tries to comfort her. Richard's father seeks for his help. He's being sued by his former secretary for sexual harassment. He fired her because he was falling in love with her, which damages his 40 yearlong marriage.
Will's life is about to change as he is sent to find the person responsible for leaking information to him about SD-6. Meanwhile, Sloane finds himself on the cusp of finally tracking down Khasinau when SD-6 captures "The Man's" right-hand man, Mr. Sark. Dixon becomes suspicious of Sydney's activities.
When an FBI cadet with amazing profiling skills approaches Doggett, Reyes, and Scully with a lead on a suspect in a series of recent murders, he claims the same killer is responsible for the death of Doggett's son. The agents find themselves wondering if his knowledge of the deaths is because of his obsession with the cases he has studied at Quantico, or if he is in some way involved in the murders.
Back in the general school population, the Krelboyne whiz kids wind up in cliques with jocks, skateboarders and brooding "Goths."
Clint tries to help an injured woman who has amnesia. Derek seems to be having a mid-life crisis. Raul and his friend Justin discover on-line gambling.
Hank is shaken after having a dream about grilling burgers...naked...with Nancy. And the situation is stirred when Peggy finds out.
Bill is heartbroken when the beautiful jogger he's pining for falls for Boomhauer, who is in turn heartbroken himself when the jogger dumps him.
David and Keith continue trying to iron out their problems...and Karla has a secret that isn't going to make things any better. Meanwhile, Claire takes a curious approach to photography, Ruth prepares to move ahead with Nikolai and Brenda's engagement anxiety leads her on a sexual adventure with Melissa.
Homer and Marge discover that Apu is having an affair with the Squishee delivery lady at the Kwik-E-Mart. They decide to keep Apu's wife Manjula from finding out about it. However, she eventually learns of Apu's affair by watching store security tapes. She throws Apu out of the house and decides to file for divorce, but soon realizes that she misses him.
A client who believes he's Hannibal Lecter admits to cannibalism but not murder in a trial that's especially hard on Lindsay, whom the defendant calls Clarice.
Many years have passed since Irene left him and Soames has now decided that he wants a divorce. He's met an attractive young woman, Annette Lamotte, who with her mother runs a restaurant in Soho. He asks Young Jolyon, who is trustee of the legacy his father left her, to ask if she could provide him with grounds for divorce. She assures Jolyon that there has been no one in her life, a message he relays to Soames who refuses to believe it. He even visits Irene but unable to find grounds for divorce, he decides that he wants her back. All he manages to do is frighten her into fleeing to Paris. Val Dartie is disgusted by his drunken father, Montague Darty, who he sees cavorting with courtesans in a casino. Montague decides to abandon his family and leave for Buenos Aires. Soames insists that his sister Winnifred institute divorce proceedings. Val and Jolyon's daughter Holly strike up a close friendship. When they agree to marry, Holly's brother Jolly intervenes challenging him to join the army and go to South Africa.