Ryan, Marissa, Seth and Summer are about to begin their senior year at Harbor High. But while everyone else celebrates the last days of summer, a dark cloud hangs over the foursome. Trey, Ryan's brother, still clings to life two months after the shooting and the cops want to know who really shot him. Meanwhile, Julie Cooper and Jimmy are determined to protect Marissa at whatever cost. And while Sandy, Seth and Ryan try to fend for themselves at home, Kirsten, still recovering in her plush rehab by the sea, forms a friendship with fellow recovering alcoholic Charlotte, who like all things in the O.C. may not be everything she appears to be.