It's hard to explain it without spoiling it, but I'll give it a shot. It's essentially about an aristocratic family, the Crawleys, and their downstairs help. It starts with the sinking of the Titanic and marches through the early parts of the twentieth century, and there's a lot of British snark and humour and some pretty good will they, won't they with some of the characters. And Maggie Smith. Lots of Maggie Smith.