After Lucas and Keith learn that Dan had a heart attack and is still in the hospital, they decide it is best for them to return to Tree Hill. When Deb learns about Haley and Nathan's marriage, she grows hostile. Meanwhile, angry that Lucas left Tree Hill without saying goodbye, Peyton and Brooke try to mend their friendship.

With the assistance of Peyton and Brooke, Lucas throws Nathan and Haley a wedding reception. Although Haley's parents support the 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. Nathan gets a job working for Keith at Dan's dealership.

Brooke's new neighbor quickly makes his presence felt among the Tree Hill gang and even comes to Brooke's rescue when she is caught shoplifting. Nathan and Haley have their first post-wedding argument when he buys her a gift rather than a much-needed car. Lucas' attempt to help Dan with rehab ends in disaster when Dan reverts to his old ways. Peyton tries to organize an all-ages club and is tempted to try cocaine to seal the deal.

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, and the two of them seem to hit it off. 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 Dare Night resulted in new arrangements, a midnight meteor shower finds Lucas sharing a romantic night with Anna. Andy surprises Karen with a dinner and Keith cooks for Jules on their first date. Brooke finds herself forming a mutually beneficial relationship with Felix, and Peyton sets out to find an opening act for her club.

The opening of Karen's club "Tric" brings together the people of Tree Hill. Lucas and Felix come to blows over Anna. After Chris quits his gig the night of the club opening, Haley must face her fear of performing to save the night for Peyton. Although Mouth tends to Brooke while she is drunk, Felix sneaks in and attempts to take the credit. Keith and Jules realize their relationship has reached a new level, while Dan deliberately tells Karen that Deb slept with Keith.

The girls of Tree Hill have a slumber party, at which time secrets are revealed and bonds are made. Meanwhile, Nathan and Lucas road trip to Charlotte for a basketball game, and unknowingly to Lucas, they embark upon free HCM tests, a genetic heart condition that Dan maintains. Karen and Andy have a row.

Lucas takes Anna to the formal night but by the end of the night ends up with Brooke. After spending time with Chris, Haley arrives late to the formal which angers Nathan. Meanwhile, Peyton struggles with pressure to do drugs.

Nathan is concerned about Lucas' health, so he tells Karen that Lucas didn't take the heart test. Dan offers Keith to continue working at the dealership-as vice president. At school, Peyton must confront the rumors going around that she is a lesbian. This affects her friendship with Anna. As for Nathan and Haley, they begin to grow apart...

Haley is surprised when her older sister Taylor comes to town, but not as shocked as Nathan, who recognizes Taylor from a past tryst. Brooke and Felix decide to become boyfriend and girlfriend. Jake makes a special visit to Peyton. Anna tells a secret to Lucas.

Nathan comes clean with Haley about his past relationship with Taylor, although Haley continues to email Chris without telling Nathan and Taylor finds out. Lucas and Karen remain at odds over his refusal to take the HCM test. Keith proposes to Jules. Meanwhile, Brooke fights for better working conditions at her new job. Lucas decides to take the HCM test.

When Michelle Branch & Jessica Harp from the band "The Wreckers" perform at TRIC, Haley realizes her passion is to pursue her music career. Meanwhile, Lucas decides to move in with Dan, straining his relationships with both Karen and Nathan. Brooke runs for student council president, but quickly realizes she is taking on more than she bargained for. Peyton and Jake's friendship grows stronger. Brooke finds out that Mouth broke her car window. Lucas gets his HCM results and aren't what they turn out to be.

As his marriage with Haley continues to go wrong, Nathan goes into a emotional crisis and becomes the "bad" Nathan of the past. Karen continues to struggle and try to figure out what would cause Lucas to move in with Dan. Peyton and Jake's relationship gets greater.

When Tree Hill High does a time capsule project, the gang confesses their most intimate secrets to an anonymous video camera. Nathan's anger over Haley's absence continues to grow, landing both Lucas and Nathan in jail. Peyton and Jake's feelings for each other heat up, while Felix throws Brooke a party to celebrate her new gig as student body president. Meanwhile, when brought to court, Lucas opts to live with Dan and Deb rather than Karen.

Keith and Jules' wedding day, and the event has turned the town upside down. Brooke asks Lucas to take her to the wedding as his date, Nathan makes an important decision involving his marriage to Haley, and Jake and Peyton take a big step in their relationship. Meanwhile, Karen and Andy discover Jules' secret relationship with Dan.

Keith gets violent with Dan after learning that Dan paid Jules to fall in love with Keith. Anna turns Felix in to the school authorities after learning that he was the one who vandalized Peyton's locker. Lucas and Brooke discuss Brooke's possible move. Meanwhile, Nathan chances Haley in the hope of bringing her home. Brooke decides to move in with Karen.

On his way home from seeing Haley, Nathan stops to visit Taylor hoping for some fun and maybe more. Meanwhile, Anna gets a surprise visit from her ex-girlfriend and is inspired to tell her parents about her sexuality. Also, Lucas works with Andy to bring Dan down, Karen puts her foot down with Brooke. Peyton and Jake continue to hide baby Jenny from Nicki.

Nathan's Uncle Cooper comes into town to take Nathan and Lucas on a racing trip. On the track, Nathan and Lucas are challenged to a race by the beautiful Daytona and her smart aleck brother Jarret, but things go horribly wrong when Nathan loses control of his car and crashes into a wall. Meanwhile, Deb's addiction to pain pills intensifies and Dan exposes Andy's relationship with Karen to his class.

Lying in a coma after his race car accident, Nathan dreams of what life would have been like if Dan had stayed with Karen and Lucas instead of marrying Deb. In this imaginary world, Lucas would have had the wealth and stature and Nathan would have been the one growing up on the wrong side of the tracks. After waking up, Nathan phones Haley and tells her he doesn't want her to come home.

Nathan is released from the hospital and returns home to a pile of unpaid bills and an eviction notice. Lucas, Peyton and Brooke throw a fundraiser Tric to raise money, but Dan is the one that comes to Nathan's rescue. However, his gift comes with strings - he wants Nathan to ask Haley for an annulment.

In the first part of the two hour second season finale, things heat up between Lucas and Brooke after they head to New York for an overnight stay with Haley. Peyton is elated when she gets the band Jimmy Eat World to perform at TRIC in time for Jake's release from jail. Meanwhile, Andy invites Karen to spend the summer in New Zealand.

In the second part of the this seamless 2-hour Season Finale of "One Tree Hill," things heat up between Lucas and Brooke since he finally tells her what he feels about her. Nathan and Deb conspire to desert Dan for good, leading to an explosive conclusion when he discovers their plan. Peyton has a shock. Meanwhile, Karen decides to spend the summer holiday in New Zealand. And at the climax of Dan's numerous deceptions someone sets the dealership on fire with him in it.

In the third season premiere, we finally discover Dan's fate after the fire. Besides the situation with his father, Nathan also has to deal with Haley's reappearance in Tree Hill and the future of their relationship. Meanwhile, Peyton tries to find the truth about the mysterious woman who pretends to be her mother. Also, Lucas looks forward to Brooke's return after a summer apart.

Brooke has an end of the summer party on the beach. As Nathan comes home from basketball camp, Haley tries to tell him how she feels.

Elsewhere Lucas deals with Brooke's rules for dating and Peyton deals with family issues.

Nathan asks Haley for a possible divorce. Lucas tells Dan that he saved his life. Peyton finds out something deep about Ellie. Dan tries to drop accusations at several people about the fire. He also tries to get Whitey replaced as Ravens coach.

It's Halloween in Tree Hill and everybody is celebrating at Tric, with special guest band Fall Out Boy. The masquerade ball gives the opportunity to Haley to win back Nathan while Brooke is trying to seduce Lucas. Also, Peyton decides to face her new mother and get to know her; Dan uses blackmail to become mayor but things don't turn out as easy as he thought they would when Deb gets in his way.

The Ravens begin basketball practice. New team captain Nathan clashes with Lucas over Haley, and a new cheerleader sets her sights on Lucas. Elsewhere, Dan's mayoral bid takes a surprising turn when an unlikely opponent emerges, Karen.

Brooke makes a "Fantasy Boy Draft," after all of the cheerleaders are fighting over the same guys. Haley and Peyton continue to argue over Nathan. Dan butts heads with Karen because the election is drawing nearer. Lucas is trying to keep up with the fast pace of basketball.

The fantasy draft dates begin, Lucas finds himself with Rachel and a very familiar setting. Brooke is on a double date with an unusual couple. Mouth and Peyton hang out again. And Peyton regrets the things she says to Ellie. Karen and Deb take the campaigning for mayor, to a new level, to bring down Dan. Nathan gets mad when Chris gets close to Haley.

As the town readies for the Ravens' first basketball game, Lucas worries that his head and heart aren't in it. Nathan accuses Lucas of being the Ravens' weak link. Peyton and Haley mend fences to support Brooke in a time of need. When the mayoral race tightens, Dan resorts to a smear campaign.

It is revealed that Lucas knows who tried to kill Dan and he confronts the guilty party. Brooke, Peyton and Haley find themselves behind bars. Peyton finds her guilty conscience on the surface. Chris Keller convinces Nathan to be his wingman at a high-stakes poker game. The residents of Tree Hill finally choose a mayor.

Lucas and Peyton take a road trip together to find Ellie. While out of town, Lucas reconnects with a friend from his past. Brooke, Haley and Mouth successfully launch the Clothes Over Bro's website, only to find that demand far exceeds supply. Deb reveals to Nathan that she tried to kill Dan.

The Ravens lose their second game in a row, so Whitey teaches them a tough lesson. Peyton and Ellie look for support for their album and hope to attract Nada Surf to the project. Meanwhile, both Dan and Haley upset Nathan, while Brooke plans a romantic thank-you for Lucas.

As the students meet with the school counselor to plan for the future, Nathan and Haley realize they want to attend different colleges across the country from one another and Brooke discovers Rachel's reasons for submitting her designs to Rogue Vogue. Meanwhile, Ellie and Peyton bond as they finish the benefit album.

A violent rainstorm knocks out the power in Tree Hill, leading Haley to Nathan's doorstep and Brooke out into the downpour for a dramatic confrontation with Lucas. Peyton finally confronts the truth about Ellie's illness, while Mouth is tempted by his new friend, Rachel. Before morning, secrets are revealed, relationships are tested, and new love gets hotter than ever.

Brooke is forced to grow up in a hurry when her trip to a New York City fashion show prevents her from attending an annual cheerleading tournament. Nathan and Lucas are influenced by the father of an old friend. Struggling with her mother's cancer, Peyton joins Rachel for a night of blowing off steam, and Haley and Nathan use their hotel room as the honeymoon suite they never had.

When someone unleashes the students' time capsule upon Tree Hill High, Lucas and Mouth must confront a person from their past. Brooke has to deal with the revelation that secrets aren't the only things she exposed in the time capsule. Dan learns to forgive Keith. Haley is forced to reconcile the man Nathan was before with the man he has become, and Peyton's Breast Cancer Benefit Concert at Tric features performances by Haley, Jack's Mannequin and the return of Fall Out Boy.

Due to the aftermath of the release of the time capsule, chaos breaks out. Someone is holding students of Tree Hill hostage with a gun, shooting. While lives hang in the balance, Nathan and Lucas put themselves at risk to protect their friends and loved ones. Young lives are shattered and two lives will end.

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.

Rachel invites the gang for a weekend getaway at her family's cabin. Craziness will ensue, including a game of "I Never" which will cause characters to do things they normally wouldn't, and a nasty little issue Mouth has been harboring toward Rachel will surface. Meanwhile, Karen will confront Dan about Keith's death. Could she suspect the truth?

Lucas attempts to play in the first game after Keith's death, but cannot bring himself to do it; Nathan and Haley prepare to renew their vows, while Mouth tries to get closer to Rachel; Peyton receives a surprising offer; and Brooke finds a way to get revenge on Rachel.

Nathan deals with a player who is a rival both on and off the court. Meanwhile, Brooke and Mouth look to get even with Rachel. Dan has a run-in with Cooper; and Peyton comes to a major decision.

Haley argues about her wedding dress with Brooke during the rehearsal dinner. Elsewhere Karen and Lucas arrive back in town.

And Peyton is surprised by what she finds...

Nathan worries about Haley as they prepare to renew their vows. Peyton and Brooke's friendship becomes strained and Deb confesses to Dan about the fire.