Sonja makes hurtful accusations about Tinsley’s finances. Meanwhile, Dorinda attempts to improve her friendship with Sonja. Carole runs the New York City Marathon after months of training, but with a surprising omission in her cheering section.

The ladies head to the Hamptons for a fun-filled weekend. Tensions rise between best friends Carole and Bethenny. Dorinda and Sonja's friendship is short-lived, as a blowup at Luann's brunch sets their relationship back.

Back in New York City, Tinsley gets a surprise delivery; Carole and Luann talk through the miscommunications that have been plaguing their friendship; Luann runs into Tom's old fling; a shouting match erupts between Sonja and Ramona.

The ladies of New York are back after an eventful summer. Newly divorced Luann sits down with Dorinda and starts to open up about her relationship with Tom. Meanwhile, Bethenny mourns an unexpected death in the family. Typically reluctant to exercise, Carole preps to run the New York City Marathon. All the ladies reunite when Dorinda throws an epic Halloween party that nobody will forget.

Tensions boil over between Dorinda and Sonja at Luann’s brunch; at Ramona’s dinner party, Tinsley delivers a low blow to Sonja that shocks the whole party; Sonja calls out Ramona for not being a true friend in a text message.

Carole reveals shocking news about her relationship with Adam; Sonja prepares her townhouse; at an important business dinner in Miami with Bethenny's relief team, Dorinda jeopardizes her chances of going to Puerto Rico.

Bethenny and Dorinda hit the ground in Puerto Rico and get to work. Ramona attempts to mend fences with Sonja. Carole works on a revealing story with a magazine, while Luann starts to plan a special performance. Bethenny lets Dorinda in on an incident involving Carole’s ex, Adam. Carole confronts Bethenny about an accusation she’s made that puts Ramona in the middle of their friendship.

It's time for the ladies to make their annual visit to the Berkshires. Carole confides in Dorinda and Ramona about some tension with Bethenny, which puts Dorinda in an uncomfortable place. All of the ladies get decked out for a 1920's murder mystery dinner party taking place at Blue Stone Manor, but it's an argument between Carole and Bethenny's that has the ladies guessing whodonnit?

Carole and Bethenny continue to hash out their issues during the murder mystery dinner party. Back in the city, Bethenny's holiday party is interrupted by a surprise, which leads to hurt feelings. At Luann's blood drive, Carole is upset when she finds out that Bethenny has been talking about her behind her back. Then, Ramona confronts Bethenny on an epic sidewalk phone call. In a shocking turn of events, Luann gets arrested over the holiday.

Two weeks after Luann's surprising arrest, she is still the talk of the town. While she's in rehab in Palm Beach, the ladies try to piece together what happened. Bethenny throws a launch party for her new jeans line, and later meets Carole for lunch to try and resolve their dispute. Sonja flees her construction site and spends a night with Tinsley. Dorinda takes the initiative to check-in on Luann in rehab.

Tinsley tries on wedding dresses with her mother, Dale. While Luann is ending her stint in rehab, the women tough it out during a prison style workout. A few of the ladies attend the funeral for Bobby Zarin, and Bethenny and Jill Zarin share an intimate moment after the funeral, for the first time in years. Luann heads home after her month in rehab.

Luann gets out of rehab and the ladies whisk her away for a spa weekend in Connecticut; the relaxation doesn't last long as Luann discovers that Ramona tried to get an invite to Tom's New Year's Eve party; Dorinda and Sonja clash over a family crest.

Luann deals with the unwanted press. Dorinda confronts Bethenny the lingering tension.

Dorinda brings Luann to pick out dresses from one of her designer connections so she can prepare for her upcoming cabaret show; Bethenny creates a dating profile for Sonja; Tinsley moves into her new penthouse without Scott’s help; the women attend a speed-dating event in New York City; and the ladies decide to go on a trip to Cartagena, Colombia, as they want to escape a chilly winter.

The women arrive in Cartegena, Colombia, for their vacation; Bethenny has an allergic reaction; Luann reveals a shocking new look; an injured Ramona gets wheeled around the cobblestone streets. Bethenny clashes with Dorinda and Carole.

As the ladies head out for a day of shopping in Cartegena, Bethenny continues to unravel and the women’s patience with her begins to run out. Carole approaches Sonja for insight on Bethenny. Later over dinner, Tinsley, Ramona, and Sonja try to not eavesdrop on a heated conversation between the two distant friends. A comment Luann makes to Dorinda sends Dorinda off the deep end and puts their friendship on the rocks.

Tensions arise at breakfast as Luann and Dorinda continue their argument from the night before, as do Carole and Bethenny; the ladies ditch the city for a private island and some fun in the sun, despite the strained relations; and the day ends abruptly with a traumatic boat ride after the ladies are rushed off the island due to high seas.

Ramona shows off her newly renovated Hamptons home; Sonja stands firm on the asking price for her townhouse; Bethenny invites Dorinda to her new apartment; Adam shows up bearing gifts at Carole's athletic-chic Cosmopolitan Magazine party.

It's the night of Luann's cabaret show, #CountessandFriends. Over pre-cabaret drinks, Dorinda, Carole, and Tinsley go over some shocking guest list faux paus on the Countess's part. During the performance, Luann gets heckled, and Sonja shows some skin. At the after party, Ramona has a burning question for Bethenny and Dorinda has some parting words for Luann.

With one glaring exception, the Housewives gather to relive fun times from season 10; the women pay tribute to Bobby Zarin while questioning Bethenny's motives; they take a look back at some of their questionable wardrobe choices.

Dorinda defends herself against accusations that she may have a drinking problem; the ladies discuss Luann's absence; Tinsley reveals startling details about her relationship with Scott; Bethenny and Carole call each other out over comments.

Bethenny and Carole continuing to go shot for shot about the dissolution of their friendship; the women relive their stomach-churning trip to Colombia; Carole revisits the highs and lows of her season; Tinsley takes issue with Carole’s protests about their relationship; Sonja discusses a new chapter in her life and delves back into her issues with some of the ladies; and the women end things by sharing their biggest regrets of the season.