In the fourth book of the Borderlands sequence, Michael, Alice, Frankie and David become involved in the mystery of a vanished village The four are working on a school local history project about lime quarries and kilns. In some obscure parish recors they find a village called Philadelphia is charted but it has since disappeared without a trace and is never mentioned by the locals. intrigued, the four set out to search for clues to Philadelphia - what they find is terrifying. On the site they have begun to excavate they find a mummified body and this discovery sets off a terrifying chain of event that will take all their courage to overcome.