Sadie is the cousin of Johnny Harper. She comes to Orange County to help Johnny's mother Gwen after her son dies. She also becomes the love interest of Ryan Atwood.In the meantime, while Ryan pursues a relationship with Sadie Campbell, it becomes apparent that Volchok previously had a relationship with Sadie that only deepens Kevin and Ryan rivalry. The relationship is doomed however, as Ryan is soon afterwards accepted to Berkley and Sadie doesn't want to be the reason Ryan doesn't live his college life as he should and breaks up. She then leaves Newport to restart her jewellery-making business.