Heather hosts her own birthday bash in the Season 6 opener. Also: Aviva tries to make amends with Ramona; and the ladies are introduced to Heather's friend, Kristen Taekman.

Aviva lands a book deal for her memoir and enlists Carole for help, but their lunch quickly turns awkward when discussing the issue of ghostwriters. Elsewhere, Sonja has dinner with Aviva's former husband; and Aviva hosts a housewarming gathering.

A fiery fight between Carole and Aviva impacts a party, shocking all attendees. Elsewhere, Ramona tries to accept that her daughter is growing up, and Kristen is pressured to participate in a demanding mud run.

The women head to the Hamptons to watch Sonja perform a burlesque number at a charity event. Countess LuAnn makes her return to the group as she hosts a Hamptons barbecue at her home, where another explosive argument regarding "BookGate" leads Heather to ferociously defend Carole.

Battles continue at LuAnn's barbecue. Elsewhere, Sonja tries to clear the bitter air by hosting a brunch; Carole receives an honor at a Coney Island parade, spurring the other ladies to strut the boardwalk dressed as seagoing drag queens; and Aviva faces her greatest fear.

Ramona returns from Africa with renewed inner peace and tries to bring the feuding Heather and Aviva together; Kristen and Carole meet up with Beverly Hills housewives Brandi Glanville and Yolanda H. Foster; and Heather hosts an anniversary party.

The Fourth of July in the Hamptons leads to interpersonal fireworks. Here, Kristen and Ramona clash; Ramona and Sonja butt heads; and tensions boil over at a clambake when Aviva approaches Carole to settle differences.

Ramona reveals Sonja's financial secrets. Elsewhere, Kristen visits a new modeling agent; Sonja is stood up by her 23-year-old flame; and the heat is on at a spa when Kristen and Ramona have a dispute.

Heather invites all the ladies, except Aviva, to her vacation house in the Berkshires for the weekend. Things get dangerously out of hand when a placid canoe trip turns into a blood bath, with Kristen and Ramona going head-to-head.

Heather hosts a dinner to try to stop the bickering between Kristen and Ramona.

The ladies confront Ramona about her behavior; Kristen and Josh argue over Josh's commitment.

Sonja asks her spiritual healer to helper recover from the loss of her pet poodle.

Aviva's sex-crazed father, George, has shocking news for Cody, his twenty-five-year-old girlfriend. Aviva decides to throw them a party at a surprising, yet fitting, museum. Can Ramona and George reconcile or will their dislike for each other ruin the night? LuAnn takes everyone but Aviva and Ramona to Saratoga for a weekend of horse racing, drinking, and man chasing, but Sonja parties a little too hard and things quickly get out of hand.

Sonja's gossipy facialist spills secrets about the women to Kristen, who shares what she heard with Carole and LuAnn, who angrily refute the stories. LuAnn hosts a charity luncheon where Aviva sends around a naughty text that royally ruffles the Countess' feathers.

The ladies are set to escape the city and venture into big sky country: Montana! As their departure looms, Aviva and Ramona agree that Montana is not their dream destination. After procuring a doctor's note, Aviva opts out of the trip due to a sudden horse allergy and asthma condition that nobody is buying. The ladies hit the ground running in Montana, strapping on their designer boots and hats before heading out on a real-life cattle drive. Later that night, in a restaurant that doubles as a stable, a peaceful dinner goes awry when LuAnn and Sonja start fighting about gossip spread by the infamous facialist.

The ladies are halfway into their Montana adventure and tension between Sonja and LuAnn still lingers. There are distractions from the drama with a full day of outdoor activities. The women become true City Slickers when they try their hand at fly fishing, skeet-shooting and repelling, but when it's Kristen's turn to descend down the mountain, things get tense. The ladies come together for a modern day treasure hunt called Geocaching, only to splinter apart again when a beer-lubricated Heather gets on Kristen's last nerve. Old friends Kristen and Heather square off in the most unexpected tiff of the season.

As Kristen and Heather continue to feud, the other ladies are all forced to take a stance.

LuAnn and Heather are chosen to perform at a jazz club. Meanwhile, Aviva makes the decision that she needs to take a break from the women.

Carole hosts a lavish party to celebrate her birthday. Sonja is presented with a present from Aviva's ex-husband Harry.

Sonja has a confrontation with Harry and LuAnn. Aviva makes her return to the group, which causes insults and accusations to be thrown around between the ladies.

The Big Apple ladies gather for a reunion hosted by Andy Cohen. Included: Ramona is cornered about her behavior toward Kristen in Montana; Aviva addresses her use of foul language in front of children; and Carole confronts Sonja about rumors and gossip.

The ladies reunite. Included: Tension surges when Aviva and Carole address their feud; drama revolves around Ramona and Heather; and LuAnn confronts Sonja about their wilting friendship.

The New York City ladies reunite. Among the dramas: Heather and Aviva clash, as do Ramona and Kristen; and the women reflect on their individual struggles during Season 6.