Mark, Jasper and Lily are high school friends now in their early twenties. Mark is gay, living with Lily (his high school girlfriend), while Jasper is straight and soon to be married. A cynical and bitter trio barely connected by their past friendship, they reunite for the annual public Halloween celebration in San Francisco's Castro district.

As the debate between Evolution and Creationism rages, 'Evolution: The Musical!' invites you to enter a world where both theories are true. In this musical tour-de-funk, we meet The Beasties, a clan of humans who have recently evolved from primates, and The Blesseds, a self-righteous religious sect who descended directly from Adam and Eve. When a brutal slaying provokes the Beasties to attack the Blesseds, all hell breaks loose and an unlikely romance throws a monkey wrench into the whole musical mess.