Hailey discovers she isn't as welcome as she might have thought. Perhaps the Cohen house is full? Luke makes some new friends, while Seth and Anna try to tell a friend about their decision. Rooney sings, a lot, and Oliver noses, a lot. Trouble brews.

Marissa plots to ruin her mother's happiness by inviting someone from her mother's past to the wedding shower, while Sandy attempts to hide Theresa's return to the O.C. from Ryan. When Ryan discovers Sandy's lies and Theresa's reasons for coming back, he puts himself in a dangerous situation. In the meantime, Seth's unimpressive first meeting with Summer's father leaves their relationship in doubt.