Sloane has always explored the Storybook Kingdom with her mom, Hannah. But when Hannah cannot join her one evening, Sloane convinces her nine-year-old brother, Carson, to take her place. Carson loves his little sister fiercely, even though her stubbornness drives him crazy-and even though his fast-moving thoughts, big emotions, and impulsive decisions sometimes create problems of their own.
What begins as one reluctant adventure quickly becomes a desperate mission when the Storybook Kingdom starts disappearing. Mountains turn into blank spaces, people forget their names, and entire stories are being erased by a mysterious figure known as the Unwriter. To save the kingdom, Carson and Sloane must travel through dangerous magical realms, recover the shattered Map of All Stories, and reach the Heart of the First Story before nothing remains.
Along the way, Carson discovers that the parts of himself others sometimes see as "too much" may be exactly what the kingdom needs. And both siblings learn that no matter how fiercely they argue, there is nothing they would not risk to protect each other.