Nathan Scott is Tree Hill High's biggest basketball star and is dating Peyton, a cheerleader. Nathan's half brother, Lucas, joins the team - and threatens to take both Nathan's spot in the lineup and his girl.

Lucas plays his first game as a Tree Hill Raven...and chokes. He isn't the only one confronting insecurities: Peyton can't find the courage to submit her drawings for publication.

Frustrated by Lucas' growing popularity at school, Nathan searches for Lucas' weak spot, and has the team begin to initiate hazing incidents against him. Nathan also tries to seek tutoring help from Haley. Brooke begins to fall for Lucas. Meanwhile, Peyton is furious with Lucas for submitting her drawings to the local newspaper without her knowledge.

Brooke takes Peyton to a college party but the night takes a bad turn when someone drugs Peyton's drink. Nathan and Haley go on a scavenger hunt date set up by Brooke in an attempt to make up for her actions at the party the night before.

After Peyton walked in on Lucas kissing Brooke the night she got him drunk, they all feel uncomfortable but decide to stay friends; Haley and Peyton even team up to organize live entertainment in Karen's café. Because of Nathan's pills-disaster, coach cancels basketball practice till further notice, telling livid Dan -who fears for the Ravens' shot at a perfect season- 'the game is no fun any more' so he takes off pressure. Nathan feels happy again taking things easy with Haley, but Dan decrees they're 'going to have a good time' on the golf weekend he planned with Deb till she threw him out, leaving the boy no escape from worrying about his parents plausible divorce in between humiliating golf 'lessons' in his dad's arrogant style, till he walks off shouting nobody can be happy with a bully like Dan. Jake shows Lucas why coach cuts him slack: his 6 months old baby Jenny, abandoned by her mother, and gets the advice not to keep that secret any longer. Jake uses the 'open mike' at Karen's to out his baby; afterward Lucas invites Nathan to the Rivercourt where all the kids enjoy informal basketball, putting coach and Keith's worries to rest.

When the doctor tells Keith it's too soon to tell how bad Lucas's injuries are, he informs Haley, who throws Nathan out immediately and calls Peyton, who is with Brooke at the time. A surprised Karen learns Dan saved Lucas by bringing him in and giving permission for surgery as his father, while Keith caused the accident under nearly illegal influence of alcohol. Karen and Deb comfort each-other at Lucas's sickbed, where Peyton briefly and Brooke more elaborately meet Karen. After Haley gives him the silent treatment, Nathan sadly admits to Deb he barely minds she's separating from Dan. Karen hears her insurance probably won't cover all the hospital bills, and finds out later that Keith paid the bill. Coach assures Karen not to doubt Keith's love for Lucas. Jake and the park court basketball gang make a get-better-video for Lucas; even Tim joins in making a chalk drawing on the court. Dan cancels marriage mediation, and isn't impressed by Deb's lawyer either, but gets a hug from Karen. Peyton tells Haley Lucas reads her soul. Nathan says at Lucas's sickbed he envies him sometimes and suggests he make up with his loved ones. Lucas wakes up with Nathan on his bedside. Nathan goes to get Haley, telling her he doesn't regret having courted her for the wrong reasons as she changed him for the better, then gives her a ride to hospital.

Lucas and Nathan bear the brunt of Dan's abuse as he coaches them into the playoffs, pushing both of them to their breaking points. Haley is stunned after Dan threatens her, causing her to reconsider her relationship with Nathan. Meanwhile, Whitey learns that his medical condition may be more serious than he first expected, and Dan learns a shocking secret from Deb.

With the assistance of Peyton and Brooke, Lucas throws Nathan and Haley a wedding reception. Although Haley's parents support Nathan and Haley's marriage, Deb has a difficult time accepting it. Meanwhile, Dan's recent heart attack causes him to try and mend his relationships with Deb and Lucas.

Although Nathan and Haley are already married, Tim insists on throwing Nathan a post-wedding bachelor party, while Brooke throws Haley a bachelorette party. Meanwhile, Lucas tries to decide whether he should visit Dan in the hospital. Karen decides to go back to school and Nathan gets a job working for Keith at Dan's dealership.

Brooke tells the Latino pool boy he's not allowed to use the swimming pool, and when he gets out finds he was skinny diving- the next morning he turns up at her school in a sports car; it's her new neighbor Felix Taggaro, who is even more flirtatious, self-confident and sassy then she and uses Mouth to find his way. At college Karen gets to know personally her business economics professor Andy Hargrove, a retired self-made tycoon. When Lucas tells he wants to use Dan's rehabilitation to get to know him properly, Nathan gives him his blessing. Dan orders Keith to fire Nathan, to no avail. When Keith advises against the second hand car Haley and he hoped to buy, he generously spends the money on a keyboard so she can work on her composing talent- and gets barked at to take it back by his ingrate wife. Peyton gets a chance to manage a famous musical duo, but only if she supplies them with and uses cocaine. While taking a sports car for a test-spin, Dan makes Lucas accept Felix' race dare, and offers him the keys- which chases him away. Deb encourages Karen finally to start her long-dreamed bar extension to the café and is asked to help run it as a club. Now she's poor, Brooke is caught shoplifting but Felix saves her bacon. Keith offers Nathan to learn car mechanics by fixing together a car/wreck he intended to strip for parts, which Nathan may then keep.

Felix organizes a "dare night" to test the limits of his new classmates. While out playing the game, Lucas meets a mysterious new girl, Anna. Peyton tearfully confesses to the church that she recently tried cocaine and Keith is caught off guard when a beautiful woman comes to the shop and begins flirting with him. Meanwhile, Karen goes on a date with Andy, her younger professor.

After the prom, Anna sleeps over at Peyton's- Felix sneers she's getting a worse reputation then his, while Peyton has a hard time with lesbianism-innuendos, even though Brooke says that appeals to boys, but ends up making a stand at school. Brooke finds Nathan slept on Lucas's floor; when he goes home, Haley tells him she respects his sacrifice and wants him to go to Highflyers, but won't do the one thing he asks, stop seeing Chris, so he walks out again and warns Chris in ominous terms and grip. Brooke blames Felix for her broken windshield and rages at him; he finds out it was Mouth, who also tells Lucas, but pays anyway; in the end he convinces her of his love. Dan takes the reins back at the dealership and offers Keith to stay on. Karen orders Lucas to take the medical test, or no basketball anyway- Nathan confesses he told her. Chris gets a chance to make a tour, asks Haley along and kisses her again. After Deb confesses her infidelity with him to Karen, Jules gets a call from Keith he loves her, and reports it to Dan

While Nathan is unconscious in the hospital, he dreams a nightmare alternative version of his life, in which Dan married Karen and lives with her and Lucas, while Keith is the successful car dealer, Dan is assistant coach and trains Lucas as the Ravens star. Nathan is the poor underdog living with Deb -who runs the café- but may still be recommended for Highflyers by coach Whitey if he wins a duel; Haley is his girlfriend, Brooke makes a pass at him. Karen cheats on Dan with Keith. Peyton goes steady with Lucas but tells Haley to warn Nathan about Lucas' dirty plans; Dan's attempt to bribe Nathan off actually motivates him to fight, so he is abducted, bound and dumped by Lucas's Ravens hardcore. Peyton dumps Lucas, who loses the duel after she picked Nathan up.

Nathan is recovering and back home, but won't tell Lucas what drove him. Brooke pieced together a shredded invoice Lucas sneaked home, so she learns about his investigation for Dans car dealership scam, and Andy makes sense of it but feels Lucas should stop taking risks. Nathan was relieved to hear his hospital bills are all paid, when Dan bursts in; he refuses to move back home even during revalidation, but keeps annulment forms. The kids planned a benefit film night for Nathan's medical bills, and go on just for the fun; to their surprise he appreciates an accidental films switch showing car accidents. After talking to Peyton he wants to forgive his ma for fleeing into pills, as she begs in a letter, but understands his insurance wasn't paid, so he sees Dan who confirms he paid, the rent too, and ends up believing he could be on the road to becoming a bitter bastard like him if he makes the wrong choices; he even asks Lucas to back off his investigation and decides to return home; Haley got her annulment petition offered by Dan too. Andy shows Lucas the profits went largely in a college fund for him; he moves back to Karen when Nathan returns.

Lucas and Haley dig up, as each year, their previous predictions for the new school year; he decorated Brookes locker- they are arranged alphabetically, making the Scott brothers and Haley neighbors. Mouth pod-cast-interviews Ravens-star Nathan. Dan warns coach Durham he plans to have the school board remove him and Lucas he remembers his arson. Ellie tells Lucas the marijuana is for her cancer pain. When Haley asks coach for help with Nathan, he just gives her a detention slip for entering the boys locker room- Nathan is there to, but pays her no attention; next day, same place, they talk a bit. When dad Larry and Ellie wait for Peyton, she storms out blaming Lucas for 'trapping' her; left alone, dad makes her consider a shrink. Karen reminds Nathan how desperately he wanted Haley back. Dan tells the board the Ravens can be North Carolina state champions without Whitey, Karen praises his lessons on life for the boys- he stays on, but gives Mouth a scoop: he'll retire next year. When Dan nearly chokes Lucas, Peyton stops him and makes him tell he didn't start the fire but found Dan and dragged him out- Lucas now regrets that, Dan says a real man had left him and demands secrecy. Haley is happy to hear Nathan considers an annulment a lie, not when he proposes a divorce instead, hopeful again when he says the legal one year- waiting period gives them time to reconsider.

In an effort to keep her cheerleaders from fighting over the same guys, Brooke devises a `Fantasy Boy Draft', Haley and Peyton butt heads over Nathan, while Lucas has trouble keeping up with the brutal pace of basketball practise. Meanwhile, as the election nears, mayoral candidate Dan clashes with his new opponent.

As the fantasy draft dates begin, Brooke finds herself on an unusual double date, while Lucas gets closer to Rachel. Meanwhile, Karen and Deb take their campaigning to new heights.

Lucas and Peyton take a road trip together to find Ellie. While out of town, Lucas reconnects with a friend from his past.

The aftermath of the school shooting and the death of Jimmy Edwards forces everyone in Tree Hill to examine their lives. Nathan reassesses his relationship with Haley, while Brooke and Rachel join forces to heal the student body. Dan must deal with the ramifications of shooting Keith, while Lucas and Peyton consider the implications of their kiss in the library.

On the night before Nathan and Haleys wedding, Brooke argues with Haley over the wedding dress. Meanwhile, Lucas and Karen return.

Nathan and Haley's wedding is a time of great joy. And great sadness. Peyton and Brooke fall out, Dan learns the truth about the fire, and Rachel gets publicly drunk....and publicly bitter.

The aftermath of the post-wedding car accident unfolds. Haley is deeply affected by Nathan's attempt to rescue Cooper and Rachel, Brooke confronts Lucas with her true feelings and Peyton makes a startling discovery. Pressured by the fact that someone might know he killed his brother, Dan assaults Deb.

As Nathan, Rachel and Cooper's lives remain precarious following the car accident, Brooke celebrates her 18th birthday but finds it diminished by her struggles with Peyton. Lucas and Karen come to terms with her pregnancy and with the pregnancy of someone close to Lucas, while Deb's past addictions intersect with Haley in an explosive manner.

Nathan and Haley's financial struggles force Nathan to approach Dan for help. In spite of his heart condition, Lucas decides to rejoin the Ravens, teaming him with Skills. Feeling isolated and alone, Peyton finds comfort from an unlikely source, while Brooke begins dating again, but discovers that her new boyfriend is not all that he seems to be. Mouth receives an unexpected proposal, and an old acquaintance of Dan's, Daunte, shows a sudden interest in Nathan.

On the day of Prom, the residue of Nathan's pre-Prom party has serious repercussions for everyone in Tree Hill. Haley asks Nathan for a list of his past sexual conquests. Rachel is suspended after taking the blame for the exam she stole with Brooke. Peyton tells Lucas she wants to skip the Prom entirely, but he refuses to take no for an answer. Finally Mouth and Brooke must deal with dating Clean Teens on Prom night.

Nathan and Haley grow closer in spite of the recent scandal. Brooke wonders if a spark might be rekindled with Chase. Peyton receives a tempting offer that would ultimately take her away from Tree Hill. Mouth reconnects with Gigi, while Lucas tells Karen that Dan is a murderer, setting off an explosive series of events.

As graduation day dawns in Tree Hill, some dreams begin as others end. Haley prepares for her graduation speech and her role as a young mother, while Nathan prepares for life without basketball. Brooke makes a heartfelt confession that puts her future in jeopardy. Lucas confronts Dan as Karen's life is threatened.

Dan must face the harsh consequences of his decision to murder Keith as Karen and Haley's pregnancies complicate the lives of Nathan and the graduating seniors of Tree Hill High. Lucas wrestles with his post-high school options, and Peyton and Brooke prepare to spend the summer in Los Angeles together.

As promised, Lucas, Brooke, Nathan, Haley, Peyton and their Tree Hill gang meet up after 4 years of being apart. Haley and Nathan still live in Tree Hill with their now 4 year-old son, James Lucas Scott. Nathan's dreams of being a NBA star were smashed. Peyton has just quit her job in the record industry. Brooke is living in New York. Her multi-million dollar clothing line, Clothes Over Bros, has given her a successful career in fashion design. Lucas comes back Tree Hill with his new girlfriend, Lindsay, suffering writer's block. The group rekindles to see how much their lives have changed since the simple years of high school

Nathan's depression hits rock-bottom, to the point of ignoring Jamie, so Hayley warns she may leave him. Uncle Lucas steps in as father figure when Jamie enters a go cart competition. Lucas takes the coach job for his high-school team the Ravens, assisted by Skills, but most promising player Quentin Fields is an arrogant idiot, who must be suspended due to his misbehavior in Hayley's class. Nathan nearly drowns himself but hen decides to pick himself up for Jamie's sake. Brooke decides to invest in a record label for house-mate Peyton to run. Nathan and Hayley hire a foxy nanny.

Missing Nathan gives Jamie nightmares about Dan, who is indeed paroled. Lucas and Lindsay decide to 'coincidentally' have separate stag and hen nights at the same place, so Nathan and Haley are bound to meet. Brooke arranges a hot blind date for Peyton, but the joke is on her as Owen's chosen mate is Chase, Brooke's former 'clean teen' lover. Jamie's tireless efforts to get his mom and dad to make up In turn make Haley realize she shouldn't have tried to change Nathan. Ruthless business adviser and absent mother Victoria pushes Rachel out, to Brooke's disgust.

Lindsay's big day, the wedding to Lucas, has finally arrived. The old gang reunites, remembering their own loves and/or marriages, even Karen and Andy from New Zealand. Haley still isn't ready to let Nathan back. At the altar Lindsay finally realizes the Comet in Lucas' book refers to Peyton's car and their first love, and runs out. Crazy Carrie kidnaps Jamie, pretending she was rehired as his nanny. Because Haley saw Dan and refused him entry, Nathan sends the police look for his dad. In fact Dan followed Carrie and finds his grandson.

Lindsey returns to Tree Hill for Jamie's fifth birthday party, giving Lucas hope for their relationship. Brooke and Peyton prepare for life with a new baby. Meanwhile, Dan tries to insinuate himself back into the lives of his family, ultimately divulging a grave secret to Nathan and Haley.

Lucas returns from Las Vegas and learns of the tragic death of Quentin Fields, as Nathan and Haley struggle to find a way to help Jamie understand the death of Quentin who was a close friend of theirs. Lucas, Skills, Nathan, Haley, and Peyton go to visit Quentin's mom and give their sympathies. Jamie meets Quentin's brother, Andre.

Nathan and Haley must parent Jamie in the face of a school bully, while Lucas and Peyton adjust to life as a live-in couple. Brooke finds being a role model not as easy as she expected, and Marvin gets his old job back. Marvin is surprised to find out that his new intern is someone from his past.

In a very special episode, Chad Michael Murray pens an homage to the classic films of the 1940s. Karen's Cafe is transformed into a glamorous nightclub with Lucas as its proprietor, Nathan as the bartender and Haley as the nightclub's resident singer.

As news of Peyton's condition spreads, Marvin and Millicent struggle to remain a couple and Brooke tries to suss out Julian's intentions. Peyton and Lucas babysit Jamie and his friend, while Haley and Nathan spend a night out together with Chase and Mia.

Lucas wrestles with casting for his movie while Peyton tries to prepare for their future. Dan advises Jamie on a school crush. Brooke meets the actress who will play her while Nathan gets exciting news, and Haley has to make a tough decision at school.

Warned by manager Bobby there's an NBA scout, Nathan and his protégé Nino perform excellently, then wait for a call. Lucas opposes Peyton preparing a 'posthumous' time-capsule and ask for a rushed marriage on account of her pregnancy risk. Nathan makes him reconsider and drops off Jamie with 'his uncle Keith'. Brook, Sam and Victoria are too busy to concentrate on Peyton's baby-shower or business. They are preoccupied as to whether Sam should be encouraged to spend time with birth mother Rebecca.

Peyton and Lucas' wedding day has finally arrived and surprise guests attend. Haley plays an unexpected role in the ceremony while Nathan hopes to be called up to the NBA. Antwon keeps Jamie on a short leash, and Brooke does the same with Nick Lachey.

Victoria bails Millicent out of jail the morning after her arrest and tells her to get herself together before she shows herself again. But Victoria is doubtful that Millicent has learned her lesson and proceeds to keep an eye on her and she is proved correct when Millicent steals a dress from Brooke's new collection to give to her model friend Makenna is exchange for a packet of blow. Mouth is distraught at the change in Millicent and they break up. Clay tries in vain to hold onto his one client but it is not to be and so he packs up his apartment much to Quinn's dismay. Nathan is told by his agents that he won't play NBA this season and his only option is to play in Spain and be ready for the next season but this move coincides with Haley's planned record tour of the US. Skills records a video with the help of Jamie for a new job in L.A. Elsewhere, Julian mistakenly tells Alex that Brooke cannot have children which further deepens the rift between Brooke and Julian after Alex tries in her own way to help Brooke. Despondent after being told to stay away from Julian Alex slits her wrists in the bath and leaves Julian a voice-mail telling him she won't bother him anymore.

Flashback to the '80s.

Nathan and Haley struggle with the aftermath of her mother's death, while Brooke deals with the fallout of Alexander's tryst with Victoria. Alex discovers a secret about her leading man, Josh, that could derail Julian's film, and Quinn is confronted by an unhinged Katie.

Nathan is furious when his first mission as Clay's junior agent seems to go wrong because of his lack of jargon knowledge, but he actually lands the football client. Julian accepts Alex's suggestion to assemble all potential best men for a friendly poker night, but the mood is murderous. Chase gets abused by everyone. It's Brooke's turn to be bullied by Julian's bossy ma who pushes for a traditional wedding at a brides fair, where Haley - blaming pregnancy hormones - sides with the enemy every time.

Julian finally sells his One Tree Hill series concept to a studio and is hired to complete the script. Clayton and Quinn, who welcomes Sara's memory to, patiently win Logan's trust to become a warm; close family. Chase gets over his confidence crisis as bar manager just before he's offered a chance to buy Tric from Karen on the boat burning day. After Julian scolds father-in-law a useless father and Brooke 'surprises' her divorced parents back in bed, an unexpected business move makes up for a lot.