When she was a girl, Autumn dreamed of fairies and magical adventures--but those adventures weren't her imagination after all, and the reality is more dangerous than she ever thought possible.

As a child, Autumn Ackerman believed that Santa Claus and his army of talking teddy bears were the creators of the universe. She lived in a fantasy world where her imaginary friend, Barnaby, accompanied her on amazing adventures. But after her father walked out on her and her mom, the magic quickly faded from Autumn's life, leaving her to ask the question: Why live in a world without teddy bears and Santa Claus?

Now a high school senior, Autumn is bogged down by stress and anxiety about college and is stuck working a minimum-wage job at a local coffee shop to help her mom financially. Just when she would give anything to have the tiniest bit of magic back in her ordinary life, Barnaby reappears and turns the imaginary into reality by introducing her to the fantastical world of the Night Folk, real-life creatures behind the legends of trolls and monsters.

Led into this dark and dangerous reality, Autumn encounters characters such as the legendary October King, the treacherous Mr. Balloon, and many others whose lives are closely intertwined with hers. As the story of her family's past begins unfolds, Autumn is guided on a path of self-discovery fraught with danger and mystery at every turn.