Susan is dismayed to see her ex-husband, Karl, emerge from Edie's house one morning. She runs over to confront him and he admits he's sleeping with Edie and may move in with her. When Edie comes by—on rollerskates—to apologize for not telling her, Susan pretends not to care and gets in her car to drive away. Edie brags that Karl told her that sex with her was the best of his life. Susan snaps back that Karl told her he's still in love with her and recently asked her to come back to him. She drives off, Edie still in pursuit, and after their ensuing argument, accidentally backs up into her. Meanwhile, Mike wants to know where their relationship stands now that they're not moving in together. Susan says she wants to keep it "casual," but he doesn't know what that means. "We can still go see a movie," she explains, as he comes closer. "Anything else?" he asks and as he starts to kiss her, she says, "Brunch. We can go to brunch!" and runs away. Rex's mother Phyllis publicly embarrasses Bree when she starts crying over Rex's death. So Bree slaps her. She apologizes later, but with Bree's uncanny composure and her eagerness to settle Rex's will, Phyllis starts to suspect Bree isn't sorry Rex is dead. The doctor treating Rex finds the note he wrote before he died, forgiving Bree, although it doesn't say why. The suspicious doctor hands it to the lead insurance investigator. The same investigator Phyllis calls when she sees Bree being comforted by the ever opportunistic George. Gabrielle's outburst last time she visited Carlos - about him being a rich man - means unless he pays a violent inmate off, there'll be hell to pay. She agrees to deliver $7,000 to the guy's girlfriend, but it's for breast implants she doesn't want. Gabrielle quickly agrees she doesn't need them and takes the cash back. The next time she sees Carlos, he's been badly beaten and he orders her to convince the girlfriend to take the money. She refuses, unless he gives her control of their bank account. Lynette is dismayed to come back from a long day at the office to find the house is a pigsty and Tom already in bed. The final straw is when she realizes he didn't change the bed after the baby threw up in it. She starts changing the bed around him and he tells her she has control issues. She leaves him the bed and goes to sleep on the couch. While flipping channels she comes across a horror film about rats and has a brainstorm. The next day she lets loose a rat in the house and waits for it to have the desired effect. When she comes home, the house is spotless. Tom admits he let the house go too far but that the rat inspired him to clean. And that he killed it with a shovel. She's both pleased and horrified by the news. She goes to take out the trash and apologizes to the dead rat, but also thanks it for saving her marriage. Susan asks Betty about the strange clanging noises she's been hearing coming from her house in the middle of the night. Betty pretends not to know what she's talking about but then the noise comes again. She explains that it's just her son, Matthew, but then he walks up behind them, having just gotten home. Betty says a quick goodbye, leaving Susan more suspicious than ever. Betty complains to her psychiatrist that she can't sleep, telling him how her husband used to beat her and how she still has nightmares because she wasn't able to prevent him from killing their son. The doctor prescribes a sleeping pill, which she grinds up and puts in the food she brings to the chain-rattling captive in her basement.
Title reference
The episode title, You Could Drive a Person Crazy is a song from the Stephen Sondheim musical, Company.
