On their first day of summer vacation, three teenage friends get into a brawl with a local biker gang. One of the bikers is killed. The following day, the boys are pursued and cornered by the rest of the biker gang at a local swimming hole. A frightening creature rescues the boys, and in a savage instant of violence and horror, the bikers are no more. The boys are pulled, kicking and screaming, under the water and into a world that was written about by Homer millennia ago, but was only thought to be a myth. The boys must find an ancient hero and defeat an evil overlord if the creatures who summoned them are ever to help them return home.