"The Vulnerables" is an extraordinary novel about a woman at war with herself. The woman--Sigrid Nunez--is living alone through COVID in New York City. There are reasons for despair. Nunez recalls a quote from Stephen Hawking in 2017: "Humanity has 100 years left on this planet." Nunez takes long walks through the semi-abandoned city, and one day, a stranger in a balaclava parks his bike in front of her. He pulls up the mask and coughs in her face; he rides away. On another day, Nunez visits a coffee shop she loves and chats with the barista who ranks at the top of her "favorites" list. She absentmindedly rests her hand on the counter, and the barista--enraged by the life of an "essential worker"--snaps at her. This takes her breath away. On still another occasion, she opens hate mail from a stranger who has read her first book, "A Feather on the Breath of God." The stranger has concluded (1) the novel is not a novel but a memoir, (2)...