One had a secret, the other made a promise.
Hanna and Nic were inseparable as kids - until she moved away with no notice and didn't contact him for three years. Imagine Nic's surprise when they run into each other days before the start of their senior year. They quickly pick up where they left off, but Nic can tell that Hanna is hiding something. When Hanna finally opens up to Nic, he decides that he will do anything to protect her - even if it means hurting the ones he loves most.