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 ladies journey to the Hamptons to see Sonja perform in a burlesque act for charity. Elsewhere, LuAnn returns to host a Hamptons barbecue, but a fiery argument erupts.

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.

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.

Kristen worries about Sonja's business plan and enlists her business-minded husband to analyze it. Meanwhile, Carole meets with a matchmaker; and Heather invites all the ladies, except Aviva, to her vacation home, where Ramona stirs up tension.

Heather tries to bring peace to the clashing Kristen and Ramona with a dinner. Meanwhile, the ladies take a hike in the woods, but Ramona stirs up tension when she faces a childhood fear; and the women relax, sunbathe, swim and flirt.

The ladies confront Ramona about past behavior. Elsewhere, marital dissension plagues Kristen; LuAnn invites Carole on a double date; and Ramona sets out to make peace with Kristen.

Sonja reaches out to a spiritual healer. Meanwhile, Kristen auditions for a workout video; Aviva's father returns with a surprise; and the ladies assemble for a memorial for Sonja's dog.

Aviva's father delivers shocking news to his 25-year-old girlfriend, and LuAnn hosts a weekend getaway of horse racing and partying, leading to rising drama when Sonja celebrates a little too much.

A Saratoga trip ends with a wives-gone-wild night on the town. Later, Ramona bonds with Avery before her college departure; Sonja's facialist spreads gossip to Kristen; LuAnn throws a charity auction; and Aviva hosts an art party.

The ladies head to Montana, where they take part in a cattle drive. Later, there are beefs at dinner when LuAnn and Sonja clash over gossip spread by a facialist.

A Montana trip continues with tensions lingering between Sonja and LuAnn. Meanwhile, the ladies participate in outdoor activities and a modern-day treasure hunt, but the group divides thanks to a tiff between Heather and Kristen.

Heather and Kristen continue to clash, forcing some of the women to take sides. Elsewhere, the ladies take in a rodeo show and a final outdoor Montana dinner.

The wives return from Montana as Aviva discovers she's been the butt of jokes. Meanwhile, Ramona's husband prepares for an open-mic gig. Heather and LuAnn are also slated to perform, but drama soars when LuAnn backs out.

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.

Part 1 of 3. 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.

Part 2 of 3. The details of the "Bookgate" feud unravel; Ramona explains her dislike of the Berkshires; Luanne confronts Sonja; Andy asks Ramona about the state of her marriage; LuAnn retaliates against Ramona.

Heather and Aviva butt heads; Kristen stands her ground when Ramona tries dismissing her; Ramona and Sonja defend their relationship; the ladies discuss the incident at Le Cirque.