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.