At the moment, there are no chapter summaries available on eNotes, and policy prohibits me from directing you to outside, competing sources. I can give you our resources, but for what you want I'd advise you to read the book itself. It will give you better insight than reading someone else's summaries. I can also recommend that you spend some time online searching for essays; there are several that might help you with understanding the book.
A brief summary:
Mary Jamison is kidnapped by Indians; they sell her to two Seneca Indian sisters, who "adopt" her as a replacement for their dead sibling. They teach her Native American ways and she makes friends. At the end, when she has the opportunity to return to her original way of life, she remains, choosing her adopted family.