After Thanksgiving, Anna (recurring guest star Samaire Armstrong) and Summer (recurring guest star Rachel Bilson) remain upset with Seth for his behavior on the holiday, and Seth struggles to reconcile with them. Meanwhile, Julie (recurring guest star Melinda Clarke) has relationship problems of her own. Jimmy and Sandy team up to tackle Jimmy's legal issues. A secret indiscretion by Kirsten is exposed. Ryan and Luke become partners on a history project, and an astonishing revelation creates an unexpected alliance between them.

When Seth tries to choose between dating Summer (recurring guest star Rachel Bilson) or Anna (recurring guest star Samaire Armstrong), he ends up in the middle of a very complicated situation. Meanwhile, Ryan visits his brother, Trey (recurring guest star Bradley Stryker), in prison, accompanied by Marissa. When Julie (recurring guest star Melinda Clarke) finds out that Marissa is with Ryan in Chino, she becomes furious. As everyone nervously waits at the Cohen house for Ryan and Marissa to return, tensions mount, making the holiday a Thanksgiving to remember.

Seth excitedly introduces a skeptical Ryan to Chrismukkah, a Cohen family tradition that resulted from Kirsten being Christian and Sandy being Jewish. As everyone prepares for a huge holiday party organized by Julie (recurring guest star Melinda Clarke), Seth continues attempting to juggle Anna (recurring guest star Samaire Armstrong) and Summer (recurring guest star Rachel Bilson), both of whom want to date him exclusively. Meanwhile, on opposing sides of a lawsuit, Sandy and Kirsten dread working through the holiday season, but Kirsten learns something about her father that could change everything. And Ryan and Marissa's shopping trip leads to trouble--and the beginning of even bigger problems for Marissa.

Kirsten's rebellious 25-year-old sister, Hailey Nichol (recurring guest star Amanda Righetti), comes to town on New Year's Eve, causing turmoil in the Cohen household. Ryan and Marissa plan a quiet evening of popcorn and movies at home, but Marissa later decides to attend a party hosted by a young man, Oliver Trask (recurring guest star Taylor Handley). Meanwhile, Hailey persuades Sandy and Kirsten to go out so she can have a raging party in their house for a few friends. As the clock ticks closer to midnight, Ryan hopes that he can make it to Marissa in time for their first New Year's kiss together. As of this episode, Melinda Clarke as Julie Cooper and Rachel Bilson as Summer Roberts are series stars.

Kirsten's company does not charge Ryan with arson for the model home burning, but he must remain in juvenile hall until he can be placed in the care of a guardian. Kirsten reluctantly brings Seth to the jail to visit Ryan. During the meeting, a violent inmate almost assaults Kirsten, but Ryan bravely defends her. Fearing for Ryan's life, Kirsten takes temporary custody of him. After hiring a private detective, Sandy locates Ryan's struggling mother, Dawn (recurring guest star DAPHNE ASHBROOK), and brings her to Orange County for an uncomfortable reunion with Ryan. Dawn has left her abusive boyfriend and wants to work on her drinking problem and be Ryan's true mother again. Meanwhile, Marissa's father, Jimmy, borrows $100,000 from Kirsten to save his faltering financial business. Since Kirsten and Jimmy dated long ago, Sandy and Jimmy's manipulative and judgmental wife, Julie (recurring guest star MELINDA CLARKE), are concerned when they find out about their spouses' secretive behavior. At a casino night

Melinda Clarke

The cast answers "The OC" Insider Question.

The cast answers "The OC" Insider Question.

The cast answers "The OC" Insider Question.

The cast answers "The OC" Insider Question.