It's party time in Tree Hill. A masquerade ball at Tric provides the perfect opportunity for Haley to win back Nathan's heart, and for Brooke to seduce Lucas. Punk-pop sensation "Fall Out Boy" performs amidst the costume madness, while Peyton tries to come to terms with the new mother in her life. Meanwhile, Dan gives Deb an ultimatum, but soon finds she's a much more worthy opponent than he thought.