The Tree Hill gang deals with the aftermath of the limo accident. Dan offers his help to Karen, and Lucas strengthens his friendship with Peyton, who gets some surprising news; Brooke does as well, and she makes a new friend from an old rival.
Brooke reluctantly celebrates her 18th birthday with Rachel; Nathan continues to struggle with his part in the limo accident; an unstable Deb brings a gun to the cafe; and Dan reaches out to Karen as his guilt over Keith's death continues to haunt him.
Nathan tries to shake his unease on the court, but memories of the accident continue to bother him; Rachel steps up her pursuit of Nathan as Lucas gives up on Brooke; and Peyton spends some quality time getting to know Derek.
Nathan struggles with money problems and reluctantly asks Dan for help; Brooke learns the new man in her life is also her new English teacher; Peyton gets help from an unexpected source; and Lucas returns to the Ravens just in time to help the team advance in the playoffs for the state championship.
Peyton returns to school, but she breaks down; Brooke's fashions are a hit at the local show; Nathan is cornered into a no-win situation by Daunte (Rick Fox); Deb takes drastic action for her addiction.
As the Ravens prepare for the championship, Lucas learns Nathan intends to throw the game and decides on a risky plan to even the odds; Karen insists Deb show up for her son's final game and tries to help her get there; Dan makes a last plea with Daunte.
After a cardiac incident, Lucas has a dream in which the spirit of Keith visits and shows him how much one life can affect the lives of others, with a nod to "It's a Wonderful Life." Elsewhere, Haley is the victim of an accident and Dan helps out Nathan.
Lucas tries to get back to normal after his heart attack and to reconnect with Peyton; Haley learns of Nathan's involvement with her accident; Dan faces murder charges; and Deb leaves rehab---but not with the doctor's blessing.
The approach of the senior prom causes Haley to be even more frustrated by her injuries; Skills and Mouth come up with an interesting plan to help Nathan's money troubles; Brooke gets closer to a new guy in town (Stephen Colletti) at Rachel's expense.
Karen worries when Lucas persists in pursuing theories about Keith's murder, so Dan suggests they get him some professional help. Meanwhile, Peyton considers doing a music internship in L.A.; Haley runs into roadblocks with her valedictorian speech; and Brooke tries reconnecting with Chase through yearbook signatures.
Karen is hospitalized after suffering some complications with her pregnancy. As graduation nears, Nathan ponders his future and Brooke feels guilty about the stolen calculus test. Meanwhile, Skills and Bevin's parents meet for the first time.