The memory thief / Jodi Lynn Anderson.

Enhanced descriptions from Syndetics:

"This expertly crafted story thrums with magic, love, and tense action." -- Booklist (starred review)

Perfect for fans of The Girl Who Drank the Moon , this fantastical and heartfelt first book in a new trilogy from critically acclaimed and New York Times bestselling author Jodi Lynn Anderson follows a girl who must defeat thirteen evil witches.

Twelve-year-old Rosie Oaks's mom is missing whatever it is that makes mothers love their daughters. All her life, Rosie has known this...and turned to stories for comfort. Then, on the night Rosie decides to throw her stories away forever, an invisible ally helps her discover the Witch Hunter's Guide to the Universe , a book that claims that all of the evil in the world stems from thirteen witches who are unseen...but also unstoppable. One of these witches--the Memory Thief--holds an insidious power to steal our most precious treasures: our memories. And it is this witch who has cursed Rosie's mother.

In her quest to save her mom--and with her wild, loyal friend "Germ" by her side--Rosie will find the layers hidden under the reality she only thought she knew: where ghosts linger as shades of the past, where clouds witness the world, and a ladder dangles from the moon leading to something bigger and more. Here, words are weapons against the darkness, and witch hunters are those brave enough to wield their imaginations in the face of the unthinkable. The knowledge of her beloved stories is an arsenal in this world, but to unlock their power, Rosie must dare to have hope and believe in herself in the face of daunting odds.