Alexis is shocked when Vicki invites her to a party at Tamra's new gym -- but not as shocked as when she finds out that Tamra says it's OK. Lydia makes a splash when she reveals that she's been invited to Tamra's party -- by her old friend Alexis Bellino. Meanwhile, Gretchen and Slade try to keep their relationship strong while dealing with challenging personal issues close to home. Then, on the night of the big party, Tamra wonders if she's made a huge mistake by allowing Alexis to come when things quickly spin out of control.