Downton Abbey Sunday at 9 p.m., Channel 2

The prettiest soap opera of them all returns, with lots of new joys and, in particular, tragedies for our beloved Crawleys and their cadre of servants. The future of the house itself is one of the season’s big themes, as is the return of Sybil and her working-class husband. Shirley MacLaine (above) appears in Sunday’s two-hour premiere, as Cora’s American mother.