How to disappear completely

"While her grandmother was alive, Emma's world was filled with enchantment. But now Gram is gone, and suddenly strange spots are appearing on Emma's skin. Soon she's diagnosed with vitiligo--a condition that makes patches of her skin lose their color--and the magic in her world is suddenly replaced with school bullies and doctor appointments. But when Emma writes one last story in the journal she shared with Gram, something strange happens. Someone writes back to her, just like Gram used to. Who's writing to Emma? And just what is her story going to be, now that everything is so different?"--Provided by the publisher.