Winner of the 2016 PEN/Bellwether Prize for Fiction, awarded by Barbara Kingsolver for a novel that addresses issues of social justice, The Leavers (Algonquin, $25.95), by Lisa Ko, is an exploration of the lives of a family of Chinese immigrants.  Polly, an undocumented immigrant, is rounded up in a raid on the nail salon where she works, gets caught up in the system, and eventually is repatriated to China.  Her eleven-year-old son doesn’t know where she’s gone or what happened to her. She’s just gone.  Fostering with a kind, intelligent couple (both are professors) in the suburbs, Deming has difficulty recovering from the trauma and confusion of his early life.  The book is timely and the subject important, but the strength of the novel lies in the composition of the principal characters, showing the depth of their humanity, their worthiness of our empathy.