Willa, the eponymous main character of the novel Willa of the Wood, is a talented twelve year old girl who has been given the task of stealing from her human neighbors by the leaders of her clan, called the Faeran clan. To that end, she spends much of her time creeping around the cabins of humans at night, stealing what they wouldn't miss. This is incredibly dangerous work - work not suitable for an older person, no less a twelve year old.
Just like most other young people, Willa is a curious girl and wants to learn more about the world around her. One day, her curiosity gets the best of her and she is hurt and subsequently stranded in the so-called day-folk (or human) world. To that end, in order to escape the human world, she uses the powers of her grandmother and the intelligence of her forest friends and escapes the world of the humans - humans which she and the rest of the Faeran clan have been taught to hate.
While stuck, Willa begins to learn that not all humans are inherently evil and destructive. In fact, humans are totally different from each other. Not only that, Willa learns through her experiences while stuck in the human world that her Faeran clan is not in great shape. It may even be collapsing. With this in mind, Willa must decide what to do. Should she stand up and speak out? Or should she stay silent about what she sees?