Four years after the season 4 finale, Lucas now finds himself as a writer, struggling to break into the business. He returns to the sport he loves as the coach of the Ravens along with Skills. Peyton, now in the music business, looks to find the next big thing, while Brooke works on her fashion line. Meanwhile, Nathan and Haley are raising their son, Jamie, and trying to find their way as young parents.

Lucas faces his past as he must choose the path his future will take, all while balancing the demands of being the coach of the Ravens. Haley decides to hire a nanny to lessen her load. Later, her first day of teaching does not go how she had expected. Meanwhile, Skills helps Jamie build a soap box derby racer and Mouth deals with his demanding boss.

Lucas has a sudden burst of inspiration for his writing and his editor, Lindsay, beings to wonder about the timing of this inspiration. Brooke and Peyton make business plans while Mouth continues to try to get on his boss's good side. Meanwhile, Lucas and Skills begin to get the Ravens on a winning path while Nathan continues to try to break free from Dan's legacy.

While Brooke works on Clothes Over Bro's, Peyton deals with a problem-child musician. Haley's love of music resurfaces and she soon finds her self back in the recording studio. Meanwhile, Nathan tries to deal with Quentin, but has trouble doing so; and Mouth's relationship with his boss becomes troublesome.

In a glimpse three years into the past, Lucas visits Peyton in Los Angeles with an offer that changes their relationship forever. Under pressure from Victoria, Brooke has to decide the fate of her clothing line. Whitey has doubts about Nathan when his temper flares up before a championship game as Haley has trouble balancing school and motherhood.

Lucas and Peyton square off over Lindsey while Brooke and Victoria have it out after Victoria tries to meddle with Peyton's record label. Nathan begins to connect with Jamie's nanny and Haley continues to butt heads with Quentin. Meanwhile, Mouth must decide between his co-workers or his affair with his boss, Alice.

It's just like old times again when the Tree Hill gang come together to see The Honorary Title perform at Tric. Peyton and Haley are able to use the event to introduce their musical act, while Carrie uses it to get closer to Nathan. Brooke sets Mouth up on a blind date with Millicent and Lindsey confronts Lucas over Peyton.

As Peyton confesses her true feelings to Lucas, Brooke makes a play for Owen, the bartender at TRIC, and Mouth tires to convince Millicent he's a good guy. Meanwhile, Haley must wrestle with the fact that she has information that would ruin Lucas' relationship with Lindsay, and Nathan finds himself in a situation that could end his marriage. Later, Lucas and Skills prepare for their first game of the season.

As Lucas and Skills coach the first Ravens' basketball game of the season, Haley, Brooke, Lindsay, Peyton and Mia find themselves locked inside the Tree Hill High library. Tensions in the library run high as Peyton and Lindsay butt-heads over Lucas and Brooke tries to defend her mother to her friends. Meanwhile, Mouth, who is covering the basketball game, struggles to find his story. Later, Nathan and Lucas commiserate about their decisions to tell their respective loved ones about their indiscretions.

Brooke takes Owen to New York to show him the other side of her life, but there she must face a person from her past. Haley is devastated over news that changes her marriage forever, while Nathan and Lucas decide whether or not to attend Dan's parole hearing. Meanwhile, a major record label takes an interest in Mia, much to Peyton's chagrin.

The night before Lucas' wedding to Lindsey, Lucas and Lindsey work to save Nathan and Haley's marriage while Brooke sets Peyton up with a date to the wedding -- a surprise old boyfriend. Rachel returns to Tree Hill to find the same challenges while Dan also returns, hoping to make a clean start.

In the 100th episode of One Tree Hill, it's Lucas and Lindsey's wedding day and Peyton must decide whether to intervene with the ceremony or lose her soul-mate forever. Nathan uses the event to try to mend his marriage to Haley. All are shocked when Dan, who is out of prison on parole, shows up at the event.

Lucas must put his life back together after being left at the altar by Lindsey. Nathan and Haley come together to deal with the fallout of Jamie's abduction, while Brooke must face her past as she considers adopting. Meanwhile, Peyton is visited by an old friend.

As Lucas and Peyton talk about Lucas' wedding that wasn't, Brooke gets a phone call that changes her life forever. Meanwhile, Millicent and Mouth take a large step in their relationship; Haley takes a step towards a new career; and Nathan debates how to get basketball back.

Lindsey returns to Tree Hill for Jamie's birthday party, giving Lucas a chance to try to repair their relationship. Meanwhile, Brooke and Peyton prepare for life with a baby; and Dan tries to get back into the lives of his family, which results in him revealing a dark secret to Nathan and Haley.

In the sixteenth episode (s5e16) Brooke is learning to be a parent. Lucas checks out his father’s heart condition and realizes with mixed feelings that he is telling the truth. At the same time Haley is not comfortable with the idea of letting Dan meet his grandson Jamie. Meanwhile Peyton has her own guilt feelings regarding Lucas and Lindsay’s break up.

While Lucas deals with devastating news in a violent manner, Brooke has her own emotions to deal with as Angie undergoes her surgery sooner than expected. Meanwhile, Haley debates recording a new album; Nathan pushes himself in order to get back to into shape; and Lucas reveals a shocking truth to Peyton.

Everyone must face their worst fears as Brooke grapples with returning Angie to her parents and Lucas deals with the fallout of his actions following the fight at the game. As Haley has a musical breakthrough, Peyton must deal with a ghost from her past. Meanwhile, Nathan and Jamie face their fears together.