For Dave Robicheaux, there is no easy passage home. New Orleans, and the memories of his life in the Big Easy, will always haunt him. So to return there — as he does in “Last Car to Elysian Fields” — means visiting old ghosts, exposing old wounds, opening himself up to new, yet familiar, dangers. When Robicheaux, now a police officer based in the somewhat quieter Louisiana town of New Iberia, l...