Carolyn Keene 
High Risk [EPUB ebook] 

It looks like Evaline Waters, a River Heights resident, is knee-deep in trouble. A huge corporation is suing her for her land: they want to tear down her house and put up a warehouse. And documentation of the zoning law that would protect Evalines right to keep her land is missing. Nancy is on a quest to find that document, but its hard to focus on the land when shes cruising at ten thousand feet. She and Ned are taking flying lessons! Its a good thing Nancys good at juggling more than two balls at once. Too bad shes not the only one