The narrator, a Bostonian, returns after a brief visit a few summers prior, to the small coastal town of Dunnet, Maine, in order to finish writing her book.

Soon, Mrs. Todd brings the narrator out to Green Island, in order to meet her elderly mother, Mrs. Blackett, who is well-respected by all in town and the surrounding farms.

Attending to her on the island is William, Mrs. Todd's brother, a solitary and shy older man who helps his mother tend the garden and catches fish for them in the surrounding waters.

Although initially reluctant to meet new people, and clearly intimidated by his sister's large personality, William comes to appreciate the narrator and shows her all around Green Island.

One of these tales centers on "poor Joanna," a girl they grew up with who, when left by her beau for another woman who lived further up the bay, retreats in sadness and penance to Shell-heap Island, a small deserted spot owned by her deceased father.

Eventually her way of life is accepted, as if she were an anchorite living in hermitage, and some of the townspeople pass by the island and throw things like warm clothes, tools, and extra foodstuffs up onto the shore, but without disturbing her.

After this, there are moments when the narrator begins to display a keen insight into the residents, especially when she befriends Elijah Tilley, an old fisherman lonely and widowed, who she had previously found taciturn and forbidding.

[citation needed] Jewett, who wrote the book when she was 47, was largely responsible for popularizing the regionalism genre with her sketches of the fictional Maine fishing village of Dunnet Landing.