The girls of Tree Hill have a slumber party, at which time secrets are revealed and bonds are made. Meanwhile, Nathan and Lucas road trip to Charlotte for a basketball game, and unknowingly to Lucas, they embark upon free HCM tests, a genetic heart condition that Dan maintains. Karen and Andy have a row.

Keith and Jules' wedding day, and the event has turned the town upside down. Brooke asks Lucas to take her to the wedding as his date, Nathan makes an important decision involving his marriage to Haley, and Jake and Peyton take a big step in their relationship. Meanwhile, Karen and Andy discover Jules' secret relationship with Dan.

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.

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.