As Lucas takes a trip to Hollywood to meet his film director, Nathan gets a pro basketball try-out. Peyton struggles with Mia to focus on her follow-up album, while Millicent confronts Marvin about Gigi. Julian approaches a dubious Brooke about designing clothes for his movie, and Haley takes a reluctant Jamie to his school talent show.

Julian's dad is fired as studio boss, his projects therefore in doubt. Director Reese Dixon worries about saving pay and perks, masterly. Dan's heart finally arrives, but is lost in a doggish accident. Jamie demands the truth about Keith, but stays loyal. Sam sees Jack commit shoplifting and takes both loot and blame. Julian learns the truth and must decide whether to leave Tree Hill and Brooke. Haley may return as teacher if she publicly withdraws her support for Sam's article. She leaves to join Peyton's label as Mia's producer.

Nathan and Haley are considering a better school for genius Jamie, but doubt that academic excellence outweighs posh elitism and absence of sports. Nathan is expected to step up as leader - by coaching his ingrate rival Nino. Peyton has a car accident, which wrecks Lucas' Comet on wheels. Sam's boyfriend has found cool foster parents, and must leave Victoria expects Brooke to help save the company she stole, if not out of family loyalty then for the employees.

Nathan is offered a two year pro contract, but in Europe. He agonizes whether he should take it, as Bobby suggests, or stick to his NBA dream, as Haley advices. Jamie not only does well at his first school dance, he is the one who counsels 'babsitter' Skills to date his teacher there. While Peyton grumbles bedridden, Lucas repairs the Comet as a surprise, while both reminisce. Chase must convince Mia his affair with Brooke was and could only happen before them. Haley enjoys working with Nick Lackey, who wants her to produce music.

The tree hill gang must learn that to live an exceptional life doesn't end once you've achieved your goals. With Lucas and Peyton gone, Nathan's a year into his NBA career, Haley has taken over Red Bedroom Records, and has to deal with the return of her free-spirited 26 year-old sister, Quinn. Brooke is still happy with Julian.

A disgruntled Renee makes her pregnancy known in the national media. Quinn tells David that she wants a divorce and spends the night with Clay. Mouth quits his job at the station after he is forced to report on the scandal surrounding Nathan. Brooke's fashion show is a huge success but Victoria warns her about Alex and Alex's obvious designs on Julian.

Nathan and Jamie join Haley on tour as it comes to a close. Quinn gets her divorce from David. Millicent appears in court for her DUI where Victoria offers her a job as her assistant at Clothes over Bros. Brooke finds it hard to trust Julian particularly when Alex is always by his side and ends up turning to new menswear designer Alexander Coin. Elsewhere, Haley and Quinn's sister Taylor turns up in Tree Hill with Quinn's ex-husband David who is now her boyfriend. Meanwhile, Mouth returns from L.A.

As Halloween approaches in Tree Hill, Brooke and Julian get an unexpected visitor, and Nathan begins a new career. Meanwhile, Clay and Quinn struggle with life back at the beach house, and Haley and Mia host an open mic night at Tric.

Clay finally gets some hand muscle control back. As he predicted, Nathan had no reason to be gloomy about his first contract, football talent Troy, which is signed to all parties' satisfaction. Julian and Brooke stand up to his mother, who has to back down on the fancy wedding plans but relapses into drinking. After some occupational therapy for Mouth and himself, Chase handles his Alex-Mia-dilemma. In Nathan's absence, Jamie finds it even harder to face the peril of peer ridicule for getting braces, which Haley only compounds by wearing a 'commiserative' eye-patch.

A storm strikes Tree Hill, putting everyone's life in danger.

The biggest day of Brooke Davis' life has arrived, her wedding day. Julian gets his parents to agree to a truce on their special day, but will they uphold their end? Brooke makes up with her mom, and when her dad fails to turn up, her mom walks her down the aisle. Nathan's advice of sincerity helps inspire Julian's 'best man' Jamie to make a brilliantly simple speech. Chase disagrees with Skills' absurd security-obsessed job description for them as ushers. He ends up making hotter use of the limousine.

Sex games, secrets and shoelaces all come into play as the couples of Tree Hill celebrate Valentine's Day.

As the girls plan a surprise baby shower for Haley, the guys participate in try-outs for Jamie's baseball team. Meanwhile, Brooke and Julian pursue adoption, while Mouth gets Millicent ready for her first day at work.

As Nathan, Julian and Clay coach Jamie's first little league game, the situation regarding the accident comes to a head. Meanwhile, Chase asks Alex to take a drug test for him, and Quinn gets an offer to shoot in Puerto Rico.

Haley and Brooke get ready to re-open Karen's Café as Brooke's pregnancy progresses. At her scan she discovers that she is expecting twins. Nathan and Clay set off on the road to scout new talent and it forces Nathan to finally go and see Dan. Chase leaves for the Air Force leaving behind two disappointed people - Chuck and Alex. Meanwhile, Mouth and Millie start their new morning show together but Millie is wooed away to start a new show with another co-anchor in Charlotte.

Chase is heartbroken after Alex's desertion to take the tour Chris Keller advised, yet overcomes his bitterness toward Keller, who pleads her artist temperament was a lost case from the start. Julian is near despair about the unused studio until a TV series project comes within reach. Alas coaxing the studio proves tragically incompatible with paternal duties, while Brooke charms investors for her boys fashion project with her father. Clayton's problem is worse then thought, as Quinn discovers spying on him. Haley now runs Karen's café, but her cook is sick, so Dan steps in but that costs some bigot customers, and a mystery competitor opens across the street.