In the powerful fourth season finale, the Tree Hill High School graduates share their bittersweet final moments together. At the same time, both Karen & Haley go into labor, while their loved ones stand by. Brooke has a surprising reunion with someone from her past. Peyton struggles with the thought of spending the summer away from her friends. Dan tries to assuage his guilt by making a life-changing decision. &, reflecting on the amazing journey that has brought them to the point of being true brothers, Nathan & Lucas seek closure regarding Dan.