One of a large community of deaf settlers in Martha's Vineyard, Mary has learned from her experiences that outside of her home, deaf people are despised and persecuted. She's restless living in Martha's Vineyard, but afraid of that outside world. But an old friend has written to Mary and told her about the strange feral eight year-old girl who lives at the manor house where she is serving. She begs Mary to come and see if the girl is in fact deaf and if Mary can do something to help her.
Mary realizes that she must do what she can to help the girl and so she accepts the invitation. When she arrives at the estate, she is shocked to find the girl is imprisoned, kept shackled, and frequently beaten and abused. She tries to reach out to the girl, but finds that all of her well-meaning ideals pale in comparison to the task. Humbled by the experience, Mary gradually comes to understand the girl and eventually engineers her escape for her captivity.
A much better book than its predecessor (which I will admit that I never finished), it throws light on a number of neglected facets of early American history ranging from the poor understanding and treatment of deaf people in the late 18th century to the practice of separating Native American children from their families. The woke idealism of Mary's character is gratingly anachronistic, but serves the valuable purpose of drawing attention to the norms of general society of the period. As an educational work (i.e., the sort of book one gets assigned in school) it checks off all the right boxes.
More in spite of this agenda than because of it, it's also a very entertaining book. A suspenseful story that kept up my interest and a character that gains insight and self-confidence as the novel progresses made this a much better book than its predecessor. In sum, I enjoyed the book and learned a great deal from it.