As Carrie's affair with Big goes into its third week, the scene turns from ultra-sexy to slightly seedy. In search of some chastising, Carrie turns to the one friend she knows will lay down the law, Miranda. Miranda tells Carrie that she has to stop the affair. Meanwhile, guilt-free Samantha meets her sexual match in Tom Reymi. Tom is ready to strap Samantha into his leather "swing" and go at it, but not before he is assured that Samantha has had an AIDS test, which she hasn't. Samantha is terrified to take the test, but the girls encourage her to do it. Meanwhile, Charlotte is obsessed with finding the perfect wedding gown and hires a no-nonsense stylist to help her through the process. After her recent romp with Big, Carrie is unable to relax in bed with Aidan. Still conflicted, Carrie returns to the out-of-the-way hotel where she's been sleeping with Big. As she's walking out, she runs smack into Charlotte, who sees Big and sees exactly what's going on. Later, a horrified Charlotte gives Carrie a firm talking to about the hurtfulness of having an affair with a married man. Samantha has the AIDs test, which comes back negative, and she and Tom take a erotic ride on his swing. Despite everything Carrie's been told, she breaks all rules and has sex with Big in his conjugal bed. Big leaves and tells Carrie to let herself out. Natasha returns early from the Hamptons and catches Carrie desperately trying to sneak out the back door. Natasha screams at Carrie saying she knew they were having an affair and then she trips down the stairs, smashing her lip and losing a tooth. Carrie gets her to an emergency room and waits for Big to show up. When he does, she tells him "We're so over." Big says nothing and Carrie walks out. She goes home to find Aidan faithfully waiting in her apartment.