When a rare genetic disorder steals away her memories and then her health, teenaged Sammie records notes in a journal to her future self, documenting moments great and small.

"Vanessa lives life on her own terms -- one day at a time, every day to its fullest. She can't afford to think about whether she has the same fatal genetic condition as her older sister. After all, she has way too much to do, traveling the globe and showing millions of YouTube followers the joy in seizing every moment. But lately, life has been anything but pure joy, and travel has come to an abrupt halt. After her younger step-sister drops off an...