The O.C.

The friends begin their senior year, but the cops want to know who shot Trey. Ryan tries to protect Marissa.

Sandy frets over Kirsten's attachment to her rehab friend. Marissa gets bad news from the new dean. Summer trumps Taylor when planning a carnival.

Julie and Sandy keep Ryan and Marissa apart, but Seth and Summer help them enjoy a night to remember. Taylor catches them in the act.

Marissa adjusts to a new school. Ryan wonders if their separation will affect their relationship. Seth's feud with Dean Hess gets Summer in trouble.

Ryan makes a life-changing decision with Sandy's support. Dean Hess tries to ruin Ryan's future, but Summer and Seth know a secret about Hess.

Taylor ruins Seth's night by keeping Summer away. Marissa's new friendships at public school worry Summer. Sandy forms a new partnership.

During a show by rock band THE SUBWAYS, Taylor's behavior causes a major rift between Seth and Summer.

The friends plan their futures. Marissa attends Johnny's surf competition instead of completing her college application.

Ryan works an internship for Sandy. Summer and Seth try to impress Brown University. Johnny reveals how he feels about Marissa.

Somber Summer misses her mom. Johnny's misfortune forces him to take action. Kirsten tries to make amends with Julie. Seth invents another holiday.

The friends try to get Marissa back into their school. Sandy makes a decision that could change Marissa's fate.

Marissa's sister, Kaitlin, returns home with attitude and a few secrets.

Kaitlin stirs up trouble for the gang as she prepares to celebrate her birthday.

Summer discovers the truth about Seth. Kirsten and Julie take their matchmaking business too far. Marissa tells Johnny how she feels.

Tragedy strikes the friends. Johnny's cousin arrives. Ryan questions his and Marissa's relationship. Kaitlin leaves.

Sadie and Ryan go on a road trip to find one of Johnny's relatives. Ryan returns to his old ways. Marissa is implicated in Johnny's death.

Ryan struggles to decide whom to invite to his birthday party. Julie and Dr. Roberts come clean with Summer and Marissa. Ryan and Sadie grow closer.

Ryan's nemesis returns to Newport. Taylor tries to solve Seth and Summer's problem. Marissa is all alone in Newport.

Julie and Dr. Roberts announce their engagement. Marissa seeks solace with bad boy Volchok.

The kids receive their college acceptance and rejection letters, forcing them to make decisions. Ryan and Sadie decide what do after high school.

Ryan visits his mom. Taylor and Summer wonder why Seth is keeping secrets. Julie gives Volchok stern advice.

The friends go to their college orientations. Seth sees Anna at Brown, and they instantly connect.

The senior prom brings out the best and the worst in everyone.

Ryan makes a deal with Volchok. Marissa visits Kaitlin at boarding school. Ryan forces Theresa to make a difficult decision.