Carrie unexpectedly runs into Mr. Big—and his new 27-year-old girlfriend, Natasha—at a Hamptons party. Miranda tries in vain to have some mature fun in the Hamptons. Charlotte pretends to be in her twenties so she can date a cute 26-year-old. Samantha's 25-year-old ex-assistant is hired to throw a big Hamptons party using her Rolodex for the guest list.

After learning of Big's engagement, a freaked-out Carrie tries to cope with the ramifications. Miranda sleeps with Steve for the first time after their breakup. Charlotte tries to overcome her fear of horseback riding. Samantha dates a guy who's "Mr. Too-Big", determined to overcome his over-endowment.

Carrie must confront her past with Big when she runs into Natasha, Big's wife. Miranda hires Magda, an Eastern European maid with very traditional values. Charlotte deals with some of her body issues at a spa. Samantha gets banned from Helena Rubinstein when she gets physical with a masseur.

Carrie obsesses about her perfect relationship when Aidan suggests she meet his parents. Miranda enjoys her intimate life with Steve. Charlotte gets upset when a married friend won't set her up with his bachelor buddy. Samantha tries Viagra while sleeping with a doctor.

Big tells Carrie that he's leaving his wife. Miranda deals with her breakup and Steve moving out of the apartment. After meeting the MacDougal family matriarch, Charlotte maneuvers Trey into making an "alrighty" proposal. Samantha is upset when dating a hot guy with "funky spunk".

Carrie continues her affair with Big, and tells Samantha after a girly night and Miranda after a drink on their cocktail night. Charlotte finds out by accident, when she bumps into them on the street together. No longer meeting in hotels where nobody knows them in to avoid getting caught,Natasha comes home early from the Hamptons catching Carrie in Big's apartment. She chases Carrie out, falls down the stairs and cracks her tooth. Carrie takes her to A&E where she tells Big "they are so over they need a new word for over". Miranda tries continually to get Carrie to end her affair. Charlotte hires stylist Anthony Marentino to help her find the perfect wedding dress. Samantha meets the "male version of herself", but he refuses to sleep with her because she hasn't had an HIV test.

Carrie decides, after a broad-daylight Manolo mugging, that she must clear herself of bad karma and decides she needs to talk with Natasha about her affair with Big. Miranda dates a gorgeous NYPD detective and becomes self-conscious about her own looks. Unhappily-married Charlotte struggles with her lust for a hunky gardener; she and Trey decide to separate. Samantha meets another Sam Jones, who turns out to be an NYU student and desperate virgin.