Paper Towns.

Quentin Jacobsen has spent a lifetime loving the magnificently adventurous Margo Roth Spiegelman from afar. So when she cracks open a window and climbs back into his life dressed like a ninja and summoning him for an ingenious campaign of revenge, he follows. After their all-nighter ends and a new day breaks, Quentin arrives at school to discover that Margo, always an enigma, has now become a mystery. But Quentin soon learns that there are clues, and they're for him. Urged down a disconnected path, the closer Quentin gets, the less he sees of the girl he thought he knew.