While all of the adults are away on a trip, Araminta's cousin Mathilda comes to babysit, reluctantly bringing with her two teenaged poltergeists who proceed to wreak havoc in Spookie House.
Araminta and her best friend Wanda are going on a school trip to Skeleton Island, a place rumored to be the site of a scary ghost shipwreck. And when the pair is stranded overnight, they discover that there might be more truth to the island's name than they would have preferred. Now some terrifying pirate skeletons are on the loose, and they want to take the girls down to Davy Jones's locker with them! Will Araminta, Wanda, and an unexpected friend be able to thwart the ghostly crew, avoid a watery fate, and maybe find some lost treasure to boot?