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.

Former “it girl” Tinsley Mortimer, has just moved back to the city after a tumultuous few years, including getting arrested, and is the latest boarder in Sonja’s townhouse. Bethenny invites Carole and Ramona over to discuss life, politics and Sonja’s new roommate’s tragic fall from the heights of the NYC social scene. Ramona fills Dorinda in on the dirt she has about Tom, Luann’s fiancé. Sonja throws a Mad Hatter tea party to introduce everyone, except Dorinda, to Tinsley.

The ladies go to the Hamptons for the weekend. While there: Carole is consumed with the election, Dorinda gears up to see Sonja in the wake of gossip dramas, and Ramona takes the wrong approach when asking Bethenny about a past film role.

Ramona’s Hampton’s dinner party continues and barely into the salad, Dorinda takes the conversation to a new level when she 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 her roommate Sonja.

Carole and her mom go canvassing in Pennsylvania, and later Carole and her friends watch the results at her party. Dorinda conspires to get Ramona to a surprise party she’s throwing for her, but Ramona unknowingly throws a wrench in the plans.

Carole attends the memorial service for Dorinda's late husband; Bethenny weighs moving to a larger apartment; Dorinda and the other bridesmaids get a sneak peek at Luann's wedding dress; Ramona questions Luann about not being invited to her wedding.

While out furniture shopping, Bethenny lets Dorinda know all about her new apartment. Ramona gets advice from her daughter Avery about her situation with Bethenny. Tinsley, Ramona and Sonja hit the Upper East Side for a night out on the town. Tinsley has to answer to Sonja when she meets a young suitor who does not meet all the qualifications on her list. At Dorinda’s charity event, Bethenny meets Luann’s fiancé, Tom, for the first time and Carole gets info from a friend of Luann’s 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.

Bethenny hosts her annual holiday party but doesn't invite Ramona; Luann and Tom get married; Tinsley learns that Frenchie has moved into Sonja's townhouse; Luann and Tom host a New York reception for the friends not invited to the wedding.

Sonja's love triangle gets more complicated; Tinsley goes apartment hunting; Carole and Adam bicker; Fredrik and Bethenny prepare to put her apartment on the market; Carole and Dorinda go to Washington, D.C.; Ramona throws a party at her apartment.

Dorinda fights with Sonja while at lunch in the Bronx; Tinsley breaks down; despite the tension between Ramona and Bethenny, all of the women head to Vermont; Tinsley feels as though the others are ganging up on her in regards to her life decisions.

Sonja digs a deeper grave for herself; while the women hit the slopes, a big news story about Bethenny breaks; Bethenny is on the fence about inviting Ramona to Mexico; the group plays a game of truth or dare, and Dorinda winds 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, with Ramona and Sonja scrambling for the best villa room and swiftly alienating themselves. Also, Tinsley addresses a damaging article about her, Luann takes a boozy tumble and Bethenny reprimands Sonja for her bad behavior.

It’s a new day in Mexico and the drama continues as Bethenny confronts Ramona about attending the Tequila trip. Tinsley readdresses the press article with Sonja, while some of the other ladies try their hand at surfing. The ladies all go shopping together 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 to the agave fields in Tequila. The ladies ride the drunk train back to the villa where Sonja puts Ramona in the hot seat.

Fresh off of their day trip to Tequila, 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 that leads to knives flying. Some of the ladies split off for a day of fishing and whale watching. At their final dinner Luann flubs the rules of a game.

After moving out of Sonja’s townhouse, 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 to France together. The ladies all come together when Tinsley throws a thank you party for Sonja.

In Reunion Part I, the ladies put it all out on the table, and everyone is called out for their bad and good behavior. Kicking things off with a bang, Dorinda and Sonja hash out their early season issues. Meanwhile, Luann faces more allegations about Tom from the women 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 this season.

In part II of the reunion, new housewife Tinsley opens up about her rocky re-entry into NYC life and reveals some big news. Carole reflects on the turbulent election and the status of her relationship with Adam, while Sonja discusses her personal love triangle, which elicits a shocking accusation about her French lover. Additionally, Bethenny gets emotional talking about her personal life and how she is planning to move forward.

The reunion concludes when the housewives look back on their fun-filled trip to Mexico, from Lu’s tipsy topple to the tequila-drinking marathon. 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 tearful apology. In the hot seat, Ramona is forced to address the accusations she made against Bethenny this season.