"Downton Abbey" resumes the story of aristocrats and servants in the tumultuous World War I era. The miniseries is written by Julian Fellowes and stars Dame Maggie Smith, Elizabeth McGovern, Hugh Bonneville and a drawing room full of new actors, portraying the loves, feuds and sacrifices of a glittering culture thrown into crisis. Isobel and Cora lock horns over control of Downton's medical role. Mrs. Bird starts a soup kitchen. And Matthew and William embark on a perilous patrol behind German lines.