Gloria Bonaventura, a divorced mother of three living with her 26-year-old son Nico in a sprawling house in Brooklyn, decides to participate in a new city program that would pay her to take in a migrant as a boarder. Gloria is thrilled when sweet, kind, helpful Martine arrives. But Nico is skeptical. A classic live-at-home Gen Zer with no interest in adulthood, Nico resents any interruption of his “hovercraft repose.”

As the months go by, Martine endears herself to both Nico’s sisters, while finding her way into Gloria’s heart and even, briefly, Nico’s. But as Martine’s disturbingly dodgy compatriots begin to show up, Nico conceives a dark twin hostile to both his mother’s altruism and the “migrant crisis” in general—and turns out to be anything but a reliable narrator himself.

Based loosely on a program a New York City mayor floated but did not initiate, A Better Life is Lionel Shriver at her best: smart, funny, and sensitive to the moral nuances of perhaps the most divisive issue of our times.