Half-brothers Lucas and Nathan Scott trade between kinship and rivalry both on the basketball court and in the hearts of their friends in the small, but not so quiet town of Tree Hill, North Carolina.
As the end of High School approaches, everyone finds themselves at a crossroads in their lives. Nathan survives the accident and after some initial confusion, Haley is revealed to be pregnant while Rachel turns her attentions to Nathan after Cooper leaves town, using Nathan's theory that it was really Keith who saved him from the accident to get Nathan's attention. Rachel backs off when she learns that Haley is pregnant and Nathan later learns that he had a vision of Keith and it was this vision that gave him the strength to get out of the water.
Shortly after finishing her friendship with Peyton, Brooke also breaks up with Lucas and then moves in with Rachel. Rachel sets Brooke up on a date with an older guy, Nick Chavez (guest star, Reynaldo Valentin), who turns out to be Brooke's new teacher. After Brooke dumps Nick for cheating on her, Rachel informs Brooke that she is failing calculus and together, the two girls steal the calculus test from school but to cover their tracks, they are forced to join the "Clean Teens: Virgins for Life". Newcomer Chase Adams (guest star, Stephen Colletti) also joins the Clean Teens and he and Brooke begin dating while Rachel is expelled for taking the fall for the stolen calculus test, later leaving Tree Hill with Mouth, who returns alone after Rachel goes AWOL.
Skills Taylor (Antwon Tanner) becomes a Raven and Lucas is granted permission from Whitey to rejoin the team (as long as he keeps taking his heart medication and doesn't play for more than fifteen minutes per game). In the run-up to the State Championship, Nathan borrows money from a loan shark, Daunte Jones (guest star, Rick Fox), who tells Nathan that the only way he can repay his debt is by shaving points in the semi-final and then by losing the State Championship. When the Ravens actually end up winning, Daunte attempts to run over Nathan with his car but instead hits Haley and she is rushed to hospital along with Lucas, who had a heart attack because he didn't take his medication before the game. While Lucas is unconscious, he has a vision of Keith, who shows Lucas how he has changed so many lives for the better and also tries to help Lucas remember what he saw on the day of the school shooting. Lucas wakes up with serious doubts about who killed Keith. Meanwhile, Dan is in jail, covering for Nathan who beat Daunte to death in a rage for running Haley down. Daunte's autopsy results, however, show that he was killed in the car accident he had after hitting Haley, and not by the beating he was given so Dan is released and Nathan is overjoyed to learn that both Haley and the baby are going to be fine.
