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 head to the Hamptons for a weekend of fun and an early birthday dinner at Ramona’s. Carole is staying at Bethenny’s and the only thing she can talk about is the election. Splitting her weekend between Luann’s and Ramona’s homes, Dorinda prepares to see Sonja for the first time since learning about the gossip she has been spreading about her for months . Ramona takes the wrong approach with Bethenny when asking about her film role from 20 years ago.

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 in the last moments before the presidential election, 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.

Carole attends the memorial service Dorinda has for her husband, Richard, who died five years ago. Bethenny considers upgrading to a larger apartment. Tensions between Sonja and Tinsley are on the rise as Sonja blames her for everything wrong in the townhouse, forcing Tinsley to think about moving into her own place. Dorinda and the other bridesmaids get a sneak peek at Luann’s wedding dress. Over group drinks, Ramona first questions Luann about not being invited to her wedding and then decides to confront Bethenny yet again.

Ramona gets advice about her situation with Bethenny; Tinsley, Ramona and Sonja hit the Upper East Side for a night out; Tinsley meets a young suitor; Bethenny meets Luann's fiancé, while Carole learns there may be trouble in paradise.

Bethenny discusses selling her apartment with broker Fredrik Eklund ("Million Dollar Listing New York"). Also: New rumors fly about Luann's fiancé; Tinsley's mom visits; and Dorinda hosts a birthday-holiday weekend for the ladies at her Berkshire home

The ladies join Dorinda to tell Luann about rumors regarding Tom. Meanwhile, Ramona's odd behavior at dinner throws everyone off, and conflict between Bethenny and Ramona reaches new heights.

A fight in the Berkshires between Bethenny and Ramona reaches an explosive level. In the Big Apple, Luann and Tom host a pre-wedding lunch with Dorinda and old pals Jill and Bobby Zarin. Also: Luann and Tom head to Palm Beach for their wedding.

Bethenny hosts her annual holiday party, but Ramona’s not invited. Ramona gets advice on her situation with Bethenny from her daughter Avery and Avery’s friends. Luann and Tom get married in Palm Beach on New Year’s Eve. Tinsley learns that "Frenchie" has moved into Sonja’s townhouse. Newlyweds Luann and Tom host a NYC reception for the friends not invited to the wedding.

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. Carole and Dorinda go to Washington DC for the Women’s March. Ramona throws a party at her apartment with a surprising guest list.

An old-school skirmish erupts between Dorinda and Sonja during a lunch in the Bronx. Tinsley breaks down during therapy. The ladies head to Vermont for a snowy weekend, despite tension between Ramona and Bethenny. Tinsley's life decisions are discussed.

Sonja digs a deeper grave for herself with Luann. While the ladies hit the slopes, a big news story about Bethenny breaks out online. Bethenny is on the fence about inviting Ramona to Mexico. At dinner, the ladies play a revealing game of "Truth or Dare” and Dorinda ends up attacking Luann.

Bethenny fine tunes the upcoming trip to Mexico; Carole has her day in court; Sonja gets an intimate cosmetic treatment; Bethenny is forced to face Ramona at Dorinda's dinner party; 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. Tinsley addresses a damaging article about her. Luann takes a boozy tumble. 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 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.