Luann catches Dorinda up on how her wedding plans are unfolding. Dorinda complains about Sonja's persistent bad mouthing of her. Bethenny and her realtor friend Fredrik get to work to sell the apartment she got back in the divorce. Carole has made some changes to her living situation. Luann confronts Ramona about Tom.
Tinsley Mortimer, has just moved back to the city and is the latest boarder in Sonja's townhouse. Bethenny invites Carole and Ramona over to discuss life, politics and Sonja's new roommate. Ramona fills Dorinda in on the dirt she has about Tom. Sonja throws a tea party to introduce everyone, except Dorinda, to Tinsley.
The ladies head to the Hamptons. Carole is staying at Bethenny's and the only thing she can talk about is the election. Dorinda prepares to see Sonja for the first time since learning about the gossip she has been spreading about her. Ramona takes the wrong approach with Bethenny when asking about her film role from 20 years ago.
Ramona's dinner party continues and Dorinda confronts Sonja about her incessant trash talking. Carole disinvites Ramona from her Election Night party because she doesn't believe Ramona is taking the presidential election seriously enough. Tinsley gets drinks with Luann and Dorinda, but leaves out Sonja.
Carole and her mom go canvassing in Pennsylvania, and later Carole and her friends watch the results come in while at her party. Sonja is conflicted between "Frenchie" and Rocco. Dorinda conspires to get Ramona to a surprise party she's throwing for her, but Ramona unknowingly throws a wrench in the plans.
Bethenny lets Dorinda know all about her new apartment. Ramona gets advice from her daughter about her situation with Bethenny. Tinsley, Ramona and Sonja hit the Upper East Side for a night out. Tinsley has to answer to Sonja when she meets a young suitor who does not meet all the qualifications on her list. Bethenny meets Luann's fiancé for the first time and Carole gets info that there may be trouble in paradise.
Bethenny meets with broker Fredrik Eklund to discuss selling the Mercer apartment; Ramona shows Carole a text about Luann's fiancé, Tom; Dorinda invites the women to her home in the Berkshires, where they decide to stage an intervention for Luann.
The women join Dorinda in telling Luann what they've been hearing about Tom; Bethenny urges Luann to get out now; Ramona's weird behavior at dinner throws everyone off; the conflict between Bethenny and Ramona reaches new heights.
Bethenny and Ramona's fight reaches an explosive level; Carole shows Tinsley an available apartment; Luann and Tom host a final pre-wedding lunch with Dorinda and old friends; Carole serves as host of an art opening; Luann and Tom head to Palm Beach.
Sonja's love triangle gets more complicated as things heat up with "Frenchie." Meanwhile, Tinsley goes apartment hunting. Carole and Adam bicker over items he left behind in her apartment. Fredrik and Bethenny look over her apartment as they plan to put it on the market.
Dorinda fights old school with Sonja while the ladies lunch in the Bronx. Tinsley breaks down in a therapy session. Despite the tension between Ramona and Bethenny, all of the ladies head to Vermont for a snowy weekend. Over dinner, Tinsley feels ganged up on when the group discusses her current life decisions.
Sonja digs a deeper grave for herself. While the ladies hit the slopes, a big news story about Bethenny breaks. Bethenny is on the fence about inviting Ramona to Mexico. The ladies play a revealing game of "Truth or Dare" and Dorinda ends up attacking Luann.
Back in the city, Bethenny fine tunes the upcoming trip to Mexico. Carole has her day in court while Sonja gets an intimate cosmetic treatment. At a dinner thrown by Dorinda, Bethenny is forced to face Ramona and the Mexico invite situation. Tinsley practices her flirting on a blind date set up by Carole.
The ladies arrive in Mexico and Ramona and Sonja scramble for the best room, swiftly alienating themselves from the the group. Tinsley confronts Ramona and Sonja about a damaging article. Luann takes a tumble. Bethenny reprimands Sonja.
The drama continues as Bethenny confronts Ramona about attending the trip. Tinsley readdresses the article with Sonja, while some of the other ladies try their hand at surfing. The ladies all go shopping and Ramona tries to buy her way back into Bethenny's good graces. Tinsley and Sonja's tension resurfaces at dinner. Bethenny takes the ladies on an educational day-drinking trip. The ladies ride the drunk train back to the villa where Sonja puts Ramona in the hot seat.
The ladies drink up and strip down back at the villa. Sonja spreads the love to all the ladies while Bethenny and Ramona have a nude detente in the pool. Dorinda and Bethenny get into a fight. Some of the ladies split off for a day of fishing and whale watching. Luann flubs the rules of a game.
Tinsley has Carole over to see her new digs. Luann and Tom challenge each other during a game of tennis. Bethenny deals with the stresses of renovating a new apartment, but finds distraction with a hot, new fling. Dorinda has John over for a romantic dinner, while Sonja and Frenchie talk about their upcoming trip together. Tinsley throws a party for Sonja.
The ladies put it all out on the table. Dorinda and Sonja hash out their early season issues. Luann faces more allegations about Tom and continues to defend her marriage. The Bethenny and Ramona battle takes another turn as Bethenny questions Ramona's attitude toward others and the housewives speculate on Ramona's behavior.
"Tinsley opens up about her re-entry into NYC life and reveals some big news. Carole reflects on the election and the status of her relationship, while Sonja discusses her personal love triangle, which elicits a shocking accusation about her French lover. Bethenny gets emotional talking about her personal life. "
The housewives look back on their trip to Mexico. Tinsley and Sonja attempt to clear the air and salvage their friendship. However, the reunion takes a turn when Bethenny questions the sincerity of Ramona's apology. Ramona is forced to address the accusations she made against Bethenny.