After a cardiac incident, Lucas has a dream in which the spirit of Keith visits and shows him how much one life can affect the lives of others, with a nod to “It's a Wonderful Life.” Elsewhere, Hayley is the victim of an accident and Dan helps out Nathan.

As graduation approaches, Haley prepares for the recital of her valedictorian speech and motherhood. Nathan must adjust to life without basketball, while Brooke makes a confession that may have great consequences. Lucas confronts Dan after 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.

As Brooke and Julian begin to adjust to life with their new children, Haley and Nathan find themselves dealing with similar issues. Although they don't know it yet, faces from the past threaten to interrupt plans for all their futures. Meanwhile, a mysterious problem arises for Clay and Quinn.

Brooke and her father discuss a new business venture; Julian worries about his investment; Quinn talks Clay into getting help; Millie tries to be honest with Mouth; Alex receives a tempting offer.