After a vicious fight with Stassi and Katie, Scheana must decide whether she'll still go with them on Stassi's birthday trip to Montauk. Meanwhile, Lala begins to dread Ariana's Sonoma birthday trip when she learns she'll be stuck in close quarters with Jax. Finally, Lisa must decide whether to rehire James after he makes a sincere plea to get his DJ job back.

Stassi continues her birthday trip at a Montauk clambake, where Katie finds Stassi potential new bachelors and Scheana and Kristen commit some seafood faux pas. Lala finally resurfaces to explain her disappearance, but Lisa isn't buying her wild lies. Ariana celebrates her birthday with Sandoval and Schwartz at a thrilling NASCAR race, but things grow tense after Jax disrespects Brittany. Later, Kristen, Katie and Scheana party at the Wirkus Twins' summer house, and sparks fly when Stassi finds herself alone in a hot tub with a handsome, young and successful New Yorker.