PARIS HILTON AND COLIN HANKS GUEST-STAR ON "THE O.C." THURSDAY, MARCH 3, ON FOX

When actor Grady Bridges invites Summer and Marissa to his birthday party, the girls, Ryan and Seth head to Los Angeles to join in the festivities. While at the party, Summer is thrilled with the time she gets to spend with Grady, while Seth couldn't be less happy about it. The tables turn when Seth meets Kate, and it's Summer's turn to be jealous. After the party, the gang heads back to The O.C., where Ryan has a hard time keeping Luke and Julie's affair a secret from Marissa. Paris Hilton and Colin Hanks guest-star on "The L.A." episode of THE O.C. Thursday, March 3 (8:00-9:00 PM ET/PT) on FOX. (OC-122) (TV-PG D, S)

Cast: Peter Gallagher as Sandy Cohen, Benjamin McKenzie as Ryan Atwood, Mischa Barton as Marissa Cooper, Adam Brody as Seth Cohen, Kelly Rowan as Kirsten Cohen, Tate Donovan as Jimmy Cooper, Melinda Clarke as Julie Cooper, Chris Carmack as Luke and Rachel Bilson as Summer.

Guest Cast: Amanda Righetti as Hailey, Colin Hanks as Grady Bridges and Paris Hilton as Kate.