Lee Jeno would be a math problem, if he hadn’t dropped out of school before learning how to solve equations with the degree of three to travel the world without her.

Jeno is one part confusing, two parts frustrating, and all parts out of her reach where she cannot find him. She hates him, sometimes, and other times she doesn't. He mails her postcards without a return address, crisscrossing around the world for weeks on end before her mailbox sits empty for half a year. His friends can no longer reach his old phone number. She, on the other hand, has never tried; she thinks, though, that if he had his archaic phone with him he would still pick up for her.

includes: 00 line squad, the summer four years ago with eight boys, the summer after graduation, and the summer that a new girl came to town.