Season four marks the end of high school for the major characters. Events consist of deep feelings of anger, pregnancies, wrong decisions, changing partners and falling down. Also, torn friendships are fixed and doors for love and independence open.

The main happening in this season is the murder of Keith Scott , Lucas and Nathan Scott’s uncle. It is later on revealed that the murderer of Keith is his brother, Dan. Dan is perpetually bothered by his conscience while Nathan feels Keith’s presence in the beginning of the season when he dove into the lake to save Rachel and Cooper. Nathan and Haley’s marriage hit the rocks when Nathan tries to decipher his experience. Rachel develops a sexual attraction to Nathan. Meanwhile, Brook and Lucas end their relationship, after Peyton reveals her deep feelings for him.