In Colm Tóibín’s indelibly moving 2009 novel, “Brooklyn,” set in the 1950s, Eilis Lacey emigrates from her economically depressed Irish town of Enniscorthy to New York, searching for better prospects.

Now a suburban married mother, Eilis Lacey finds herself in a quandary in “Long Island,” Colm Tóibín’s sequel to his much admired novel. By A.O. Scott When you purchase an independently reviewed book ...