In the second part of the this seamless 2-hour Season Finale of "One Tree Hill," things heat up between Lucas and Brooke since he finally tells her what he feels about her. Nathan and Deb conspire to desert Dan for good, leading to an explosive conclusion when he discovers their plan. Peyton has a shock. Meanwhile, Karen decides to spend the summer holiday in New Zealand. And at the climax of Dan's numerous deceptions someone sets the dealership on fire with him in it.

Brooke has an end of the summer party on the beach. As Nathan comes home from basketball camp, Haley tries to tell him how she feels. Elsewhere Lucas deals with Brooke's rules for dating and Peyton deals with family issues.

Nathan asks Haley for a possible divorce. Lucas tells Dan that he saved his life. Peyton finds out something deep about Ellie. Dan tries to drop accusations at several people about the fire. He also tries to get Whitey replaced as Ravens coach.

It's Halloween in Tree Hill and everybody is celebrating at Tric, with special guest band Fall Out Boy. The masquerade ball gives the opportunity to Haley to win back Nathan while Brooke is trying to seduce Lucas. Also, Peyton decides to face her new mother and get to know her; Dan uses blackmail to become mayor but things don't turn out as easy as he thought they would when Deb gets in his way.

The Ravens begin basketball practice. New team captain Nathan clashes with Lucas over Haley, and a new cheerleader sets her sights on Lucas. Elsewhere, Dan's mayoral bid takes a surprising turn when an unlikely opponent emerges, Karen.

Lucas and Peyton take a road trip together to find Ellie. While out of town, Lucas reconnects with a friend from his past. Brooke, Haley and Mouth successfully launch the Clothes Over Bro's website, only to find that demand far exceeds supply. Deb reveals to Nathan that she tried to kill Dan.

The Ravens lose their second game in a row, so Whitey teaches them a tough lesson. Peyton and Ellie look for support for their album and hope to attract Nada Surf to the project. Meanwhile, both Dan and Haley upset Nathan, while Brooke plans a romantic thank-you for Lucas.

As the students meet with the school counselor to plan for the future, Nathan and Haley realize they want to attend different colleges across the country from one another and Brooke discovers Rachel's reasons for submitting her designs to Rogue Vogue. Meanwhile, Ellie and Peyton bond as they finish the benefit album.

A violent rainstorm knocks out the power in Tree Hill, leading Haley to Nathan's doorstep and Brooke out into the downpour for a dramatic confrontation with Lucas. Peyton finally confronts the truth about Ellie's illness, while Mouth is tempted by his new friend, Rachel. Before morning, secrets are revealed, relationships are tested, and new love gets hotter than ever.