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.

Dan helps a struggling Haley at Karen’s Café. Meanwhile, Quinn discovers that Clay is hiding something from her, and Chase tries to mend a broken heart. Brooke is let down by her lunch plans with her dad, and Julian makes a life-changing mistake.

The search for Nathan becomes increasingly dangerous, and Dan’s life hangs in the balance. Brooke is surprised when her father returns. And Clay and Quinn reconnect with Logan.

As Haley prepares to emcee the annual Tree Hill Burning Boat Festival, Brooke uses the opportunity to process her father’s betrayal, while Julian tries to breathe new life into a past idea. Mouth and Millie make a change to their morning show, and Clay and Quinn get ready for Logan’s first night at the beach house.

In the final chapter of One Tree Hill, the tenth anniversary of Tric brings old faces and new possibilities for the Tree Hill family.