Lucas and Nathan Scott discover they are half-brothers with the same fatherm, and although they are different in many respects, they share a deep love of the game of basketball. Nathan is the high school basketball team's star, while Lucas is the son of a single, working mom. When fate brings Lucas onto the basketball team, a rivalry ensues, as the two compete for command of the game and the love of Nathan's girlfriend, Peyton.
Lucas makes a decision to exit the basketball team after fumbling his way through his first game. Peyton becomes more distanced from Nathan when he persists in belittling Lucas. Meanwhile, Dan's mother, Karen, refuses to watch him in action and Keith tries to get her to face up to her emotions.
Nathan tries to take Lucas down a peg by having the team faze him when he realizes that Lucas is becoming very popular. Nathan also decides to go to Haley for some tutoring, while Lucas finds himself the object of Brooke's infatuation. Meanwhile, Lucas upsets Peyton when he sends her artwork to be published in the newspaper.
Lucas is convinced by Haley to join the team at an after-game beach house party in hopes that they'll begin to bond. His taste of the good life only upsets him when he sees what his life could have been like, prompting him to confront his mother about why she accepted the cold shoulder from Dan. Nathan's mother also comes to talk with Karen, hoping to gain advice about how to handle Nathan's apparent ill-will towards her.
Lucas and Keith both participate in a "father and son" basketball game, but when Lucas takes Keith as his partner and Nathan takes their father, Dan, Lucas watches as Dan humiliates Nathan on the court. Meanwhile, Peyton finds solace on Whitey's shoulder during the anniversary period of her mother's death.
Nathan and Lucas get kicked off the team bus by Whitey after misbehaving on the basketball court, but despite being 30 miles from home by themselves, things go from bad to worse when a rowdy bunch comes by brandishing a gun and looking for trouble.
Dan and Deb hold their annual Basketball Appreciation party during which Karen finds herself making a new friendship and Keith squares off against his younger brother, while Lucas decides to make a play for Peyton. Meanwhile, Brooke's gossipy interference puts a damper on Bethany and Nathan's growing admiration for one another.
Brooke and Peyton go to a college party for a night of fun, but things get scary when Peyton is drugged by a student. Brooke calls on Lucas, who shows up in the nick of time, and the two gain a deeper understanding of one another while they watch over Peyton. Meanwhile, Nathan and Haley go out on a date after she gives him another chance to prove himself.
Nathan begins taking amphetamines to give some kick to his game after feeling like the verbal scrapes with his father and Haley are too much to handle, but the consequences are disastrous. Meanwhile, Peyton's desire to reignite a relationship with Lucas are interrupted when she spots the beginning of his and Brooke's swift attraction to one another.
When practice is cancelled, Lucas finds himself with an enticing offer, a crazy night out with Brooke. Meanwhile, Deb's hopes fior a weekend of bonding between Dan and Nathan end up veering into disaster territory when they start up with old conflicts.
Nathan quits the basketball team after feeling the pressure from Dan is too intense, and begins to fill the void by spending time with Haley. Meanwhile, Lucas and Brooke's escalating friendship switches on feelings of jealousy within Peyton.
Lucas accompanies Peyton to I.D. a body that may be her father, who was presumed missing at sea. Overwhelmed by the stress of it all, she kisses Lucas, much to his surprise. Meanwhile, when Dan's parents arrive unexpectedly in time for Dan's birthday dinner, they end up spilling the beans on some damaging information that was never meant to be heard.
When Keith and Lucas head to the airport to pick up Karen, their car is smashed by another car, leaving both men injured, Lucas more severely. When Dan, who caught the accident, takes Lucas to the hospital, he must list Lucas as his son. Meanwhile, Peyton reveals the incident of her kiss with Lucas to Brooke.
As Lucas lays in a coma, Karen rushes to his side at the hospital where she finally meets Brooke and learns firsthand that Deb is divorcing Dan. Hearing the details of the car accident, she is upset by word that Keith was drinking and driving at the time. Meanwhile, Nathan must figure out how to win back Haley's heart.
During his recovery from the car accident, Lucas begins to believe he may have made an error in starting a relationship with Brooke rather than with Peyton, and begins to secretly correct that mistake with Peyton.
Nathan is torn between living with Deb or with Dan during their divorce proceedings, but Dan tries to strongarm him into his camp by threatening to reveal Deb's secrets in court.
The group heads out to Charlotte to support Brooke in a cheerleading competition, but when a member of Brooke's team is sidelined, Peyton tries to convince Haley to fill in. Meanwhile, forced to room together, Nathan and Lucas are at each other's throats with Haley suddenly stuck in between the bickering pair.
Lucas, Nathan, and Jake become auction prizes at an annual charity function, and their subsequent dates turn into interesting reunions with some former loves. Meanwhile, when Brooke doesn't make the auction, she finds herself with Mouth and the two go out for a wild night on the town.
Lucas worries about the choice he must make when Brooke tells him she's pregnant. Meanwhile, Haley considers entering into a sexual relationship with Nathan.
Nathan decides to get an after-school job to cover the monthly apartment rent, but when Haley uses the place to throw a party, the apartment takes a drastic turn for the worse. Meanwhile, Brooke and Nicki storm the party after Brooke realizes she was snubbed for the guest list.
Lucas learns, to his surprise, that Dan fought with Karen over joint custody when he was an infant. Meanwhile, when Peyton babysits for Jake, Nicki swoops in and sneaks her daughter for a stroll while Peyton isn't looking, prompting Jake to leave town to rid his life of Nicki once and for all.
Dan's controlling ways get out of hand when he mercilessly pushes Lucas and Nathan to the limit as the playoff series approaches and he makes a serious threat to Haley about keeping away from Nathan. He is quickly shaken to the core, however, with some revealing information about Deb. Meanwhile, Whitey discovers he may be battling a very deadly illness.