Tree Hill bids goodbye to the past while anticipating the future: Lucas and Peyton prepare for the birth of their child with the help of a surprise visitor, Dan nears his end, and Brooke works with Victoria to relaunch Clothes Over Bro's. Meanwhile, Nathan returns to Tree Hill to face Haley and Jamie after being released from the Chiefs.
Lucas and Peyton's wedding day finally arrives, bringing some surprise guests along with it. Haley finds herself playing an unexpected role in the ceremony, as Skills and Brooke try to control Jamie and Nick. Meanwhile, Nathan continues to hope to be drafted into the NBA.
The families of Tree Hill draw closer as Lucas bonds with Jamie while working on Peyton's car, Sam develops a connection with Victoria, and Brooke and Haley throw Peyton a baby shower. Meanwhile, Nathan's ambitions seem closer than ever when he learns that an NBA scout will be watching his next game.
Nathan and Haley both face their dreams as he questions his ambition to play in the NBA and she receives an offer from Nick Lachey. Meanwhile, Brooke learns something that could change Sam's life forever, Jamie attends his first school dance, and Lucas and Peyton take a road trip.
The parents of Tree Hill face difficult challenges: Lucas finds himself fighting to stay calm when Peyton's pregnancy faces further problems, Nathan and Haley clash over the decision to pull Jamie out of school, and Victoria returns to tempt Brooke back into the business. Meanwhile, Mouth continues to mend his relationship with Millie.
While Julian makes Brooke a surprising offer, Lucas takes Nathan and Jamie to an important place from his past. Meanwhile, Peyton prepares for the future; Sam and Jack go up against the principal who fired Haley; and Skills and Mouth go on a road trip to help Mouth forget Millie.
As Lucas and Julian face a setback in their film production, Peyton and Haley team up to help Mia with her new single. Meanwhile, Brooke faces a crisis when Sam is arrested; and Jamie learns the truth about Dan and Keith.
Peyton and Lucas deal with shocking news about Peyton's pregnancy as Brooke and Julian face a crossroads in their relationship. Meanwhile, Nathan and Haley celebrate their anniversary, with Dan and Deb babysitting Jamie; and Mouth and Millie work to redefine their relationship.
As Lucas begins to start casting for his movie, Peyton begins to put together plans for their wedding. Meanwhile, Dan gives Jamie advise when he has his first school crush; Brooke is introduced to the actress that will play her in Lucas' movie; Nathan receives exciting news; and Haley is forced to make a tough decision at work.
Lucas and Julian have a difficult time finding the right director for their movie. Meanwhile, a present from Lucas confuses Peyton and Brooke battles with romantic complications.
News of Peyton's condition spreads like wildfire through Tree Hill. Brooke tries to suss out Julian's intentions. Mouth and Millicent strive to keep their relationship going. Meanwhile, Brooke and Lucas babysit Jamie and his friend when Nathan and Haley spend a night out together.
Peyton shares some startling news with Lucas, who discovers that Julian has been keeping another secret about the movie. While searching for runaway Sam, Brooke is forced to confront her lingering feelings over her attack. Nathan struggles with his new professional environment.
Brooke is shocked to find out that Samantha is in her room with a boy named Jack. Along with that, Julian asks her to make some clothes for the movie. Peyton tries to get Mia to focus on her follow-up album. Lucas is excited when he travels to Hollywood to meet the director of the movie. Meanwhile, Nathan gets the chance for a pro-basketball try-out. Haley takes Jamie to his school's talent show and Millicent confronts Mouth about Gigi.
Lucas falls asleep and dreams of a 1940s Tree Hill were he owns Karen's Cafe. Here, Dan is a dangerous mobster and everyone is entangled in his web: Brooke owes him money, Mouth is searching for proof that would link him to Keith's murder, Haley is his former lounge singer, and Lucas is in love with his step-daughter Peyton.
Tension arises backstage at Peyton's USO show as Lucas deals with Peyton and Julian's past. While Haley tries to find a way to ease her stage fright, Nathan grapples with a decision that could forever change his career. Meanwhile, Brooke receives a call that could end her relationship with Sam and Millicent confronts Mouth over Gigi.
Sam teaches Jamie about money. Brooke must decide whether to date Owen again, since he broke her heart the last time. Nathan comes face to face with an old rival. Meanwhile, Lucas' novel forces him to make jeopardizing decisions, and Peyton meets the movie producer, Julian.
Lucas' novel receives interest from a suprising person, as does Mouth as he meets his new intern. Jamie begins to develop a crush on Sam and her rebellious ways, while someone becomes enamored with Brooke. Meanwhile, Haley and Nathan discuss his return to baskeball as his comeback begins to look more like a reality.
Nathan and Haley must team up to help Jamie deal with a school bully. Meanwhile, Lucas and Peyton continue to adjust to life as a live-in couple. Elsewhere, Mouth tries to get his old job back.
As Lucas sets out on his book tour, he runs into a person from his past. Nathan finally gets a chance to prove himself on the court, but begins to question his health as he does so. Meanwhile, Haley reaches out to a student; Brooke debates a life-changing decision; and Peyton confronts Mick over his true identity.
Nanny Carrie continues to wreck havoc when she puts both Haley and Jamie's life at risk. Lucas reunites with Lindsey for a business meeting. Meanwhile, Brooke struggles for power at "Clothes Over Bros" after Victoria continues making unexpected decisions.
Brooke takes a trip to New York with Victoria. Peyton begins connecting with Mick Wolf, who begins telling stories about her parents. Haley continues having problems with a student and Nathan is confronted by a vision of Quentin.
When tragedy strikes in Tree Hill, Nathan and Haley experience difficulties breaking the news. Brooke still hurt over the robbery, questions her friendship with Peyton, and Lucas and Skills finally meet Quentin's mother.
Tree Hill residents are surprised to learn that a couple will indeed get married. Brooke tries to adjust to life after the robbery at "Clothes Over Bros". Nathan and Haley receive devastating news and Nanny Carrie's return creates more blanks than answers, after she kidnaps Dan - whose life is in jeopardy.
In the sixth season premiere, Tree Hill residents must make a decision that will change their lives forever. Lucas finally pursues his dream with the woman he loves, Brooke must face a reunion with her mother, Mouth makes a revelation, Nathan and Haley must face a ghost from their past and the news of Dan's accident is slowly beginning to spread.
