In the conclusion of the fourth-season finale, Katherine's secrets are revealed. But first, she begs off catering Bob and Lee's commitment ceremony, leaving Bree with her hands full. Meanwhile, Bob and Lee fight over the ice sculpture, and Tom Scavo steps in with advice; Orson keeps trying to win Bree back; Gaby gets a call from Ellie, who's on the lam; and Julie Mayer is accepted by Princeton, but Susan doesn't want to see her go.

In Part 1 of the two-part fourth-season finale, Kayla accuses Lynette of child abuse; Susan and Mike have a disagreement about their newborn son following the death of Mike's grandfather; the police close in on Ellie; Bree's pastor returns from a mission in Korea; and Katherine's two husbands, Adam and Wayne, meet.

Susan's mother-in-law visits; Carlos and Gaby learn that their tenant is hiding a dark secret; war breaks out between Edie and Bree.

Lynette finds out who was responsible for setting the fire at Rick's restaurant; Susan reconnects with ex-husband Karl; Bree gives Orson an ultimatum.

Bree and Katherine decide to start a business together; Lynette tries to deny her feelings for another man; Mike learns the truth about his nearly fatal accident.

Gaby struggles with the reality of Carlos' blindness; someone from Lynette's past shows up at the pizzeria; Bree and Katherine decide to join forces to plan the Founder's Day Ball.

Katherine can't keep some of her secrets from the women of Wisteria Lane; a surprise wedding ceremony has its share of secrets; Susan's hunky young cousin shares some unexpected revelations.

Following the tornado, Wisteria Lane residents begin to rebuild their lives, but with Mrs. McCluskey's house completely destroyed, Lynette faces the possibility that her family and Ida Greenberg didn't survive. Meanwhile, Katherine finds out that someone knows the truth about her mysterious past.

A tornado strikes Wisteria Lane, forcing residents into basements, cellars and safe rooms, and destroying homes and lives. Meanwhile, Katherine learns the truth about the relationship between Adam and his stalker.

A mysterious stalker from Adam's past shows up on Wisteria Lane; Danielle's baby puts stress on Bree and Orson's marriage; Lynette has a reunion with her long-lost stepfather; Gaby and Carlos try to figure out how to explain Victor's disappearance.

Victor confronts Gaby about her affair with Carlos; Bree tells Susan that she thinks Mike is a drug addict; the arrival of Benjamin Tyson Hodge leads to a disagreement between Orson and Bree; and Lynette and her sisters meet to discuss their mother's care.

Edie's biggest fear is realized when Carlos walks out on her; Susan finds Mike's father, who was thought to be dead; and a delivery at a Halloween party catches the Wisteria Lane residents by surprise.

Bob and Lee's front-yard water sculpture prompts the Wisteria Lane neighborhood association into action; Edie finds out about Carlos' affair with Gaby, who's also being wooed by her former gardener,

Edie receives unexpected news at the gynecologist's office; an unexpected visitor discovers that Bree's pregnancy is a hoax; and Wisteria Lane welcomes a new, male couple.

Bree gossips about what she overheard in the Mayfair house and reluctantly recommends a gynecologist to Susan; Stella makes brownies to help Lynette through chemotherapy; Edie buys an engagement ring for herself; and while Susan throws a charades party for the neighborhood, Julie and Dylan break into the locked room in the Mayfair house.

Lynette kicks Tom out of her chemotherapy sessions, Susan is mistaken for a stripper, and Bree attempts to steal a prize-winning recipe.

Former Wisteria Lane resident Katherine Mayfair moves back onto the cul-de-sac with her new husband, Adam, a gynecologist who treats Susan, and her daughter, Dylan, who can't remember her onetime best friend Julie. Meanwhile, news about Edie spreads, and Lynette's chemotherapy is wearing her down. As is the fact that she's keeping her cancer a secret. Bree's secret---her fake pregnancy---is also becoming a problem.