Faced with the prospect of returning to foster care, Ryan attempts to run away from the Cohen house, but is thwarted when Seth discovers his intentions. Unwilling to lose his new and only friend, Seth devises a plan to keep Ryan in the O.C. – offering to hide him in his mother's unfinished housing development. They receive an unlikely accomplice in their scheme when Marissa joins them, taking on the challenge of proving to Ryan and Seth that she is not the shallow rich girl they believe her to be, and creating a deeper divide between her best friend, Summer, and her boyfriend, Luke, in the process. The enclave the three of them have built is destroyed, however, when Luke and his cronies discover Ryan at the development, leading to a near fatal showdown when the house goes up in flames. Concurrently, Sandy and Kirsten discover Ryan has disappeared and question Seth as to his whereabouts to no avail, while they continue to disagree about the appropriate way to deal with Ryan.