The aftermath of the post-wedding car accident unfolds. Haley is deeply affected by Nathan's attempt to rescue Cooper and Rachel, Brooke confronts Lucas with her true feelings and Peyton makes a startling discovery. Pressured by the fact that someone might know he killed his brother, Dan assaults Deb.

Lucas receives an unlikely visitor -- his supposedly dead Uncle Keith. Haley's life and the life of her unborn child are threatened when she experiences serious complications with her pregnancy and Nathan wrestles with the guilt and consequences of his dealings with Daunte.

As graduation day dawns in Tree Hill, some dreams begin as others end. Haley prepares for her graduation speech and her role as a young mother, while Nathan prepares for life without basketball. Brooke makes a heartfelt confession that puts her future in jeopardy. Lucas confronts Dan as Karen's life is threatened.

Dan must face the harsh consequences of his decision to murder Keith as Karen and Haley's pregnancies complicate the lives of Nathan and the graduating seniors of Tree Hill High. Lucas wrestles with his post-high school options, and Peyton and Brooke prepare to spend the summer in Los Angeles together.

The big day has finally arrived and the gang gathers at the hospital to await the birth of Haley and Nathan's baby. While they wait, they reminisce about the memories they have shared over the years.

Before tired Nathan can finally rejoin his longing family, Dan has turned up and secured himself a temporary stay on account of his burnt-down restaurant, where he lived, but may have torched it. Chase is happy but exhausted on account of running the bar and an intense sex life with Alex. As if nocturnal baby care exhaustion wasn't bad enough for Julian and Brooke, his studio project only seems to bring debt and her boys fashion label fails to get financed, but her father Ted Davis actually turns up for the twins' christening. Clay's exhaustion is diagnosed medically serious. Chris Keller got engaged by Haley's music label under an alias, immediately antagonizes Alex but proves himself an genius producer.

Chase confides only in Chuck his plan to move Alex's things into his place. They ignore Chris Keller made her an offer for a career-boosting, national tour. As even the psychiatrist Clayton grudgingly consults can't properly diagnose his problems, Nathan decides with support from Jamie and Haley to attend in his pace the European forum for international sports talent scouting. This allows Dan to prolong his stay and carry out a mysterious plan. Julian warns Brooke that Victoria tries trough him to sabotage her father's apparently business-wise sound project to co-found a male fashion label.