Twelve-year-old Sayuri and her little brother Keiji find real excitement in the small Alberta town they’ve moved to, in the form of a magical Middle World behind a door in their cellar.
The last thing twelve-year-old Sayuri wants to do is move to the country, on “a trip to eternal boredom.” Sayuri loves her life in the city and her achievements as a competitive swimmer. But her father, a nurse, has found a job in rural Alberta.
Sayuri is also not impressed by the dilapidated old house they rent. One day after school, she and her little brother Keiji explore the dark root cellar and are transported to Middle World, a woodland full of figures from Japanese folklore.
When Keiji, who has serious asthma, gets lost, Sayuri must find him. A giant yamanba woman, a shapeshifter fox, and a green water sprite called a kappa all help her on her way. In the meantime, Sayuri discovers and helps attack an evil blight that has befallen Middle World.
As Sayuri struggles to battle this great evil, find her brother, and lead them both home, she finds new strength in herself and grows in wisdom. Finally, she does find her brother and together they stand before the magic Water of Possibility. They must find the courage to each take from it one good and one bad thing. When they do this, and confront their worst fears, they are also able to find their way home.