Edna O’Brien’s fourth novel, August Is a Wicked Month (1965), displayed one of the best author photographs of the 20th century. It’s reprinted on the cover of Country Girl, Ms. O’Brien’s new memoir. It depicts the young author, cigarette clasped between her middle fingers, glancing to her left at some unseen provocation. The photograph is suggestive of both innocence and experience. It seems to promise: This girl is trouble.