Julie and Dr. Roberts announce their engagement and the Cooper ladies move in with Summer and her dad. Meanwhile, Marissa drifts away from the Summer and the rest of the group when she seeks solace in the bad company of Volchok and his crew. Ryan tries to move on with Sadie, but Seth's concerns for Marissa get in the way. At the Newport Group, Sandy's woes with Matt continue and Kirsten surprises Seth with a night out.