As Edina and Patsy prepare to attend an underground rave on New Year's Eve, they receive an unexpected visit from Patsy's long-lost older sister Jackie. Patsy insists on taking Jackie along to the party, much to Edina's dismay. However, Patsy is disappointed to learn that Jackie is no longer the jet-setting, drug-addled party animal she used to be. Now homeless, Jackie asks Patsy if she could stay with Edina until she can raise money to open a shelter for stray cats and dogs. After helping Jackie loot Edina's bedroom for valuables she can sell to raise money, Patsy throws her out of the house, but it is too late to go the party a frustrated Edina has fallen asleep in the sitting room, surrounded by her family as the clock strikes midnight.

Patsy convinces Edina to hire two male prostitutes (through Edina's hairdresser Christopher) for an orgy on the night of Saffron's university presentation. However, Edina is unable to loosen up, and the prostitutes are not particularly enthused, either. Patsy attempts to enliven the mood by playing a video of an orgy she and Edina attended in their youth, only to find that it has been accidentally switched with a tape of Saffron's school project. Fearing the worst, Edina and Patsy accompanied by Mother, Christopher and his drag-queen boyfriend rush over to the university, though not soon enough to prevent a mortified Saffron and her classmates from watching the orgy tape, which shows couples having sex while Edina is asleep.

Edina becomes frustrated when she loses a prestigious PR award to rival Claudia Bing, despite having bribed the judges. Worried about her dwindling career, Edina works on a campaign in hopes of upstaging Claudia. Meanwhile, Saffron becomes romantically involved with Gerard, her psychology lecturer, until she discovers that he is married with children. In a rare occurrence, Edina comes to Saffron's aid by punching Gerard in the face. At an industry luncheon, Edina's speech is stolen, prompting a drunken rant against the bastardisation of the PR industry, which proves a success. When Edina and Patsy attempt to retrieve the speech, the duo awaken the next morning on a trash barge headed for Ostend.

Edina joins a New Age commune, but she struggles to fit in and quickly becomes bored. Patsy finds herself disillusioned with her new job in New York due to creative differences with her co-workers. Saffron settles into university life and Mother spends her days at the Monsoon house, drinking champagne and ordering items from the shopping channel. After realising that their lives are not the same without each other, Edina and Patsy happily reunite on top of Carnegie Hall Tower before returning to London. Back home, Mother has been arrested for squatting and credit card fraud. A flashforward to 25 years into the future provides a glimpse into the lives of Edina, Patsy, Saffron and Mother.