Humiliated, Nora packs up her young daughters and takes refuge on Burke's Island, off the coast of Maine. Nora spent her first five years on the island but has not been back for decades—not since that long ago summer when her mother disappeared at sea. One night while sitting alone on Glass Beach below the cottage where she spent her childhood, Nora succumbs to grief, her tears flowing into the ocean. Days later she finds a fisherman, Owen Kavanagh, shipwrecked on the rocks nearby. Is he, as her aunt's friend Polly suggests, a selkie—a mythical being of island legend—summoned by her heartbreak, or simply someone who, like Nora, is trying to find his way in the wake of his own personal struggles?