Tamra and Alexis face each other for the first time since the debacle at Tamra's party. Meanwhile, Heather and Gretchen butt heads while planning Tamra's bachelorette party trip to Mexico. Then, just as the ladies head south of the border, O.C. housewife Lauri Peterson tells Gretchen shocking allegations about Vicki's past. Will Gretchen bite her tongue or turn this fiesta into a fight?