The ladies kick off an explosive 11th season with an epic boat party as Vicki fights to win the ladies back after a year of lies left her friendless and alone. Heather's mansion is still a work in progress, and so is her relationship with her husband Terry. Shannon's marriage is on more solid footing, so it's time to look for a new home. Meghan starts in vitro fertilization (IVF) with no help from husband Jimmy. And new housewife Kelly Dodd brings her big personality to the party, but her mouth gets her in trouble.

Heather travels to Turks and Caicos to help Terry reconnect with their kids, Tamra tries to save Ryan and Sarah's relationship. As Shannon continues to rebuild her relationship with David, Vicki does the same with her business. Later, Meghan invites the ladies over to her new house to demolish her kitchen; however it's Kelly who seems to smash her chances of friendship with the girls when she reveals she has befriended Vicki.

Vicki's daughter moves back, but the homecoming falls short of Vicki's expectations. Meanwhile, Meghan begins IVF shots and confronts her fear of needles in the process; and Kelly hosts a beach party, where Vicki and Tamra try to resolve their issues.

Kelly's beach bash moves indoors as Vicki and Shannon have an icy showdown about their friendship. Also, Meghan moves closer to starting a family; Briana lands in the hospital with a medical emergency; and Shannon makes a difficult decision about Vicki.

Shannon's 1970s-theme bash is lowlighted by a hot dispute about a rumor-packed past. Also: Vicki juggles work, babysitting duties, helping Briana and partying; Heather corners Terry about his parenting; and Meghan seeks support during her IVF treatments.

Following her party, Shannon pays a visit to Dr. Moon to remove toxins; Kelly tries to make amends by inviting Shannon to sit down and discuss the night of the party; Meghan travels to Washington, D.C., to speak on behalf of colorectal cancer.

Vicki revels in the return of her family to Orange County; Heather strives to find a work-life balance; Tamra plans a sushi party as a last hurrah for Meghan, but the party goes off rails after Kelly loses her cool and crosses a line.

After an explosive night at the sushi dinner, Heather and Tamra discuss Kelly's volatile behavior as Kelly regretfully turns to her friend Meghan and receives some tough love. Meanwhile, Meghan takes the next crucial step in her IVF process. Later, Shannon celebrates a night full of surprises with all her friends and family. Back in the OC, Vicki and Kelly have a party of their own and bond over being the odd women out.

While Shannon heads to Cabo with David, Tamra and Kelly join Vicki at the luxurious Merv Griffin estate in La Quinta, California to celebrate Vicki and Briana's upcoming birthdays. Heather and Terry enjoy a date night dinner where they discuss his busy schedule and her problems with Kelly. Later, Tamra arranges a meeting between Kelly and Heather to work out their differences before the ladies head to Glamis.

Tamra, Vicki, Heather and Kelly travel to Glamis to celebrate Eddie's birthday. While the trip is supposed to be down and dirty fun, Tamra and Heather are still wary of Kelly's filthy mouth. After a long RV ride down, the ladies finally get some fresh air and see what the motor sports mecca has to offer. The next day, the ladies set out to explore the dunes, leading to a ride they will never forget. Meanwhile back in Orange County, lives are forever changed as Meghan receives the results from her pregnancy test and Shannon's holistic home has finally sold, leaving the Beador's two weeks to move out.

As the women recover from the accident in Glamis, Tamra returns intent on carrying on with the trip. New alliances form in the wake of Meghan and Shannon's refusal to visit Vicki at the hospital. Back in the OC, Tamra contemplates postponing her fitness competition. While Meghan goes to Vicki's house to make amends, Shannon attempts to get back into her friends' good graces.

Shannon panics about her families' impending move, while her daughters prepare for an upcoming rock show. Vicki celebrates Briana's birthday and makes it uncomfortably clear she is ready to fill up her love tank. The ladies come over to help Shannon purge her outdated closet; however tensions run high over unresolved issues between Shannon and Kelly, as well as Tamra and Meghan. Friends and family gather to watch the Beador girls perform, but Shannon's night is rocked by a shocking allegation from an uninvited guest.

Michael and Kelly discuss the ups and downs of their relationship since separating, while Meghan goes to her first ultrasound appointment. Vicki gets asked to film a commercial for a cancer charity. Shannon packs up her old home and gives it a heartfelt "goodbye" while Tamra hosts Kelly, Vicki, and Heather for a day of pampering and luxury at Glen Ivy Spa. Unfortunately, things at the spa aren't as tranquil as expected when Kelly tearfully opens up about her rocky marriage.

Meghan throws a party to celebrate the grand opening of her candle store. Vicki threatens to expose a secret about Shannon that leaves all the ladies confused. As Kelly and Michael try to navigate their tumultuous marriage, Meghan and Jimmy try to get a handle on her pregnancy. Meanwhile, Heather throws a party to celebrate the release of her book; where Vicki and Shannon finally confront one another.

The women jet to Ireland to explore Meghan's heritage. They embark on a pub crawl, which leads to a sobering exchange between Tamra and Kelly, pushing Tamra over the edge. The ladies then try to recover with a traditional Irish "hooley" night.

An Ireland trip continues with the ladies taking separate adventures. Meghan tries to locate distant relatives with Kelly, while the others visit a milk farm. Later, Kelly tries to make amends with Tamra, but ire rises, leaving the group in disarray.

A bus ride from hell comes to a conclusion as the ladies' Ireland trip ends. A return to the O.C. finds the women facing fallout from their getaway, and Tamra preps for her long-awaited fitness competition.

The ladies celebrate Tamra and her fitness competition with a carb-loaded affair at Shannon's new house, but drama spirals around Vicki and her loose-lipped gossip. The Season 11 finale.

Part 1 of 3. The OC ladies reassemble. Included: Vicki is grilled; Tamra opens up about religion and being a peacemaker; Meghan addresses her relationship with Jimmy; and Kelly stands her ground when '70s party accusations fly.

Part 2 of 3. A Season 11 reunion continues with Kelly on the hot seat due to her behavior. Heather has a showdown with Kelly, who reveals shocking secrets about her past; Shannon casts light on her vow renewal; and Vicki's daughter discusses her mother.

Conclusion. The reunited ladies dish on their traumatic Glamis experience, with old tensions stirred and Meghan on the defensive for her lack of sympathy toward Vicki. The drama of Ireland is also discussed, and Shannon hits her breaking point.