Nikki Griffin

Marissa throws a birthday party for Trey - an event that may or may not smooth things between the two Atwood brothers. Julie gets cozy with Lance, her long-ago lover and recent extortionist.

The evidence adds up. Trey is likely to do time for drug violations. But Sandy, Ryan and Marissa know he's innocent and develop a plan to catch the real culprit in the act. Seth meets a marketing...genius.

Sandy must make a life-changing decision to save his marriage to Kirsten. Also, Seth, Summer, Marissa and Ryan are caught in the crossfire at the bait shop, and Jimmy Cooper, worried about his family, rushes home to Newport Beach.

Heads: Seth takes Summer to the prom. Tails: Zach does. Whoever's dateless takes a meeting with George Lucas to discuss Atomic County. That'll settle things, right? The Julie-Caleb union ends...not the way anyone expected.

Nana's getting married - news that has Sandy, Seth and Ryan off to Miami. Back at the OC, Zach wows Summer with a home-cooked meal, Kirsten sorts out her Carter feelings and Trey's feelings for Marissa take a terrifying turn.

Dynamite with a lit fuse: Kirsten goes on a bender now that Carter's gone, Ryan can't figure what's up with Marissa, Caleb hits Julie with divorce papers, and the Seth-Zach rivalry turns into War of the Weirds.