Katie (Bella Thorne) has suffered from a rare disease called xeroderma pigmentosum since she was a child. Ultraviolet rays, which are very common to ordinary people, will cause fatal trauma to Katie. Helplessly, Katie can only stay at home during the day when the sun has not set, playing and composing music for fun on a guitar, but once night falls, Katie's time begins. With her beloved guitar, Katie comes to the train station and stands on the side of the road to sing and play. One day, a man named Charlie (Patrick Schwarzenegger) is attracted by Katie's singing and stops to watch. The cheerful and lively Katie makes him fall in love. What Katie didn't expect was that Charlie was the person she had secretly loved. In order to seize this relationship, Katie decided to hide her illness.