"Who's That Woman?" is the fourth episode of Desperate Housewives.
When Susan sees that Edie is trying to flirt with Mike by washing her car, she decides to interrupt it by bringing Mike a piece of junk mail that Julie had saved in case of such an "emergency". Edie quickly becomes angered and goes back into Mrs. Huber's kitchen where she tells Martha how angered she is that she is competing with Susan over Mike Delfino. Mrs. Huber uses this as an advantage since she is broke knowing that Susan was involved in Edie's house fire. Shortly after, Mrs. Huber visits Susan and offers her a piece of mincemeat pie and warns her that she knows what happened and that she won't say anything if Susan agrees to help her. The next day at the supermarket, Mrs. Huber casually puts her items next to Susan and tells her to be nice since her secret is no easy burden to carry. That evening, Mrs. Huber leaves a message on her answering machine stating she needs plumbing done at her home but can't afford it. Susan then wakes up Julie and tells her that she thinks she is being blackmailed. They both quickly decide what to do before Mrs. Huber goes to the police or worse-- tells Edie. The following afternoon while Mrs. Huber is away, Julie and Susan play frisbee which flies into Martha's yard. Julie then puts gloves on, slips through the doggy door and grabs the measuring cup. As this is happening, Susan is playing look out and Mike comes over inviting her to see a show with him. Edie then pulls up causing Susan to panic. She manages to stall them by suggesting that Mike take Edie to the show since she is busy. Edie happily agrees and at that moment Julie walks up behind causing Susan to regret what she just said.
As Lynette cleans up her house one afternoon, she receives a phone call from the twins' school and ask her to come in to talk to the teacher. When Lynette arrives at the school, she is told by their teacher that both Porter & Preston painted a little girl blue during art class. The teacher tells Lynette that this isn't the first time that the twins have misbehaved and that the school may no longer be able to accommodate the twins if they continue to act as they are. The teacher recommends that the twins go on ritalin since they show signs of ADD. Lynette objects to this and ask that the twins be separated. This attempt fails and Lynette may have to think of an alternative. She tries to give the boys their medication but when she then think they might not be the same (since they also have good qualities). Lynette decides not to give the twins their ritalin and she takes it.
Since Rex and Bree separated, the children have become even more curious on his whereabouts since Bree has not told them about the separation. Bree is finding it increasingly difficult to relate to her son Andrew since he is angered over the fact that "she has sent his father away". When Andrew goes out once again and decides not to tell Bree, she forces Danielle to call him which causes Bree to search through Andrew's room for anything suspicious. In a wooden box, she finds a match book which has the address and number of a local strip club. As Andrew and his two friends become aroused with the strippers, they become terrified over the fact that Bree is standing behind them as she catches a piece of lingerie. The two friends quickly leave embarrassed leaving Andrew to deal with his mother. She sits down next to him and tells him that she will be cleaning his room tomorrow and how he is being irresponsible. Bree manages to ruin expectations for the other men present after she gives Andrew a long lecture on how strippers are people as well. Bree and Andrew then leave. The next morning, Bree cleans Andrew's room which leads him to ask when he will be getting his door back.
Gabrielle has a relaxing bath with John but must end it when the cable guy arrives. This causes John to hurry as he leaves a piece of evidence: his gym socks underneath the bed. Later, as the cable guy finishes his work, he slips on a sud in the bathroom and is rushed to an ambulance. Carlos becomes suspicious on why the cable guy had been there so late. After finding the socks, he asks Gabrielle where they came from and she manages to lie by telling him they belong to Yao Lin, the maid. To make sure Gabrielle isn't lying, he asks John who tells him that the cable guy came at his assigned time and that he doesn't want to get in the middle. Carlos then visits Jonathan, the cable guy's house and begins to beat him yelling "Do you think you can sleep with anyone you want?" At that moment, Carlos discovers that Jonathan is gay. Jonathan than asks if this is why he beat him. Carlos says "yes" and quickly leaves. As Carlos and Gabrielle sit in the tub, they watch a news report about Jonathan's beating and show a police sketch of the suspect. Gabrielle looks back at Carlos who says nothing.
The housewives give Paul, Mary Alice's blackmail note in the hopes that it will help find her blackmailer. Paul cries and later makes up an excuse to Lynette & Gabrielle that Mary Alice was mentally ill and got worse as the years went on claiming that she was the author of her own blackmail note. Gabrielle & Lynette don't believe it and think something else was going on. Paul then gives the note to a local hitman/private eye, Mr. Shaw who tells him that he may be able to help him.