White Bostonian Turner Buckminster moves to Maine. He meets crusty, inbred Mainers and learns to love them. One especially, a black girl, who dies. Turner also learns about boats and keeping his mouth shut and not, when it's important.
I know this part of Maine and I never knew the local white people had run the black people off their island. The author could have dramatized this grandly but he makes it seem so ordinary and simple for people to be mean to each other. This is scary. Because it's historical, they simply call the mean folk "scoundrels'. We would use stronger language now.
Some of the Mainers are nice, too, including the whales.