Our narrator and protagonist is Quentin Jacobsen (Nat Wolff), who lives across the street from Margo Roth Spiegelman (whose name we hear in full more often than just her given name ... played by Cara Delevingne) and who's been in love with her pretty much his entire life. She's always been intrigued by mysteries, and when she runs away (frequently) she leaves behind clues. As they're about to graduate from high school, they've drifted apart. But one night, she climbs in through his bedroom window just as she used to - to convince him to be her get-away driver in several acts of revenge. This takes up about the first third of the movie ... but at that point, Margo vanishes. Quentin is convinced he can find her, if he follows the clues.
I expected to find some of the characters stereotyped, particularly the geeks (Quentin and his two friends). But in some ways it was Margo who was the most poorly drawn - or maybe it was that she was actually the weakest of the main actors (it's just as well she was gone for a good portion of the movie, despite being the plot motivator). The movie lays on the life lessons a little heavily, but I found some of the jokes brilliantly funny and thoroughly enjoyed it as a whole.