When Hayden Cross was sent away permanently, Ember Chance believed she had seen the last of him. She was finally able to escape his bullying, but he is back and out for revenge.
Hayden subconsciously wants to escape his bad situation when he dropped the flash drive by mistake and after learning Ember has it as she started prying on things.
Ember was taken aback as soon as Nate invited her to his party, and she immediately thought of it as their first date. She had no idea that the "date" she was expecting would hold further surprises later on.