On their way to drive Karen home from the airport, Keith and Lucas collide with an oncoming vehicle, leaving Lucas unconscious and fighting for his life. At that moment, Dan is travelling to Deb's house to plead with her to give their marriage a chance, and he witnesses the accident. At the hospital, Dan must acknowledge that Lucas is his son in order to authorise emergency surgery.
Taylor Townsend manages to seize a night with Seth by throwing a Harbor School event that keeps Summer at a distance.
Summer, Seth and Ryan launch a mission-impossible campaign to get Marissa back into Harbor; Johnny struggles between a friend's happiness and his own feelings.
Taylor's horsing around causes a major rift between Seth and Summer; Marissa vows to do whatever it takes to watch out for Ryan; Sandy's partner goes above and beyond the call of duty.
Fourteen-year-old Kaitlin Cooper (Willa Holland) makes waves when she returns home for winter break from an exclusive Montecito boarding school.