In A NIGHTINGALE, Mabel, and Vonnie, two Houston neighbors and best friends, both refugees from small Texas towns, are forbearing and patient about the protracted and uninvited visits of Annie Long, a girlhood acquaintance of Mabel's who is slipping inexorably into sanity. As uncomfortable as Annie makes them, Mabel and Vonnie are more concerned with silencing her vivid recounting of old scandals and the pain they caused.