Sean, Jason, and Zack travel to the Big Island to participate in the Showdown 2001, a 12-mile course of natural obstacles. Leigh will be taking over supervisory duties at Baywatch while Sean is away. J.D. is tending to Kekoa, who has come down with the flu. Fortunately, J.D. has an iron constitution, despite the fact that he didn't have his annual flu shot.