Who is the narrator in the novel, Volcano House?

The narrator of the story, Volcano House, is a woman in her late-30s whose sister was gravely wounded in a mass shooting while jogging. Over the course of the story, the narrator drives back and forth from her home in New York to Maine, visiting her comatose sister and offering support to her brother-in-law, Pat. She reflects on incidents that occurred on a recent vacation to Iceland she took with her sister, and these memories cause her to contemplate her personal flaws and the ways she has disappointed people she cares for.