Kirsten's father, Caleb Nichol, comes for a visit along with his new girlfriend, Gabrielle. 24-year-old Grandma Nichol has arrived. Kirsten finds her job in jeopardy, while Sandy considers making a change. Much to Ryan's disappointment, Luke decides he wants a second chance with Marissa... but who will Marissa choose? Summer makes the moves on Seth, who wonders if her feelings are real.

Back to school for the O.C. kids. No one really wants to be there, except for the gossips. Ryan doesn't feel like he fits in at his new school, and Luke doesn't make the situation any better. Sandy accepts a case at his new job, a case that will test his relationship with Kirsten and her father. Anna and Seth hatch a plan. Marissa chooses her man.

Oliver plans a trip for the gang, but things don't go as well as everyone might have hoped- except for Oliver of course. Summer really plants herself into "friendship" within Anna and Seth's relationship. Jimmy and Sandy decide to go into business together. Caleb and Julie return from Europe, and Hailey and Kirsten butt heads. Ryan finds himself in the cold.