Young Teddy and his older sister, Amanda, find themselves stranded on South Manitou Island on the second full moon of the month, or as the old-timers call it, the night of the blue moon. Little do they know that on such nights the past can come alive here, with ghosts and demons, spirits and pirates, once again walking the earth.To their amazement, Teddy and Amanda find that they have major roles to play in this magical realm on the fabled isle in Lake Michigan.