One of John Green's masterful works, Paper Towns explores the old friendship of Margo and Quentin.  Brought together as children through mystery in their neighborhood and separated by the jungle of high school, Margo shows up one night asking for Quentin's help on an epic adventure of revenge.  But when things go south after that night and Margo goes missing, Quentin is the only one with a hope of discovering where she went and going over that night over and over again to find any clues he can that will lead him to Margo before it's too late.  Throw in some high school nerds, a perfectly timed road trip and some paper town-hunting and you've got a delightful high school story of discovery and adventure.