故事发生在上世纪的三十年代，路易斯（凯莉·霍威 Keeley Hawes 饰）的丈夫意外去世，留下了四个孩子格兰特（米罗·帕克 Milo Parker 饰）、劳伦斯（乔什·奥康纳 Josh O'Connor 饰）、莱斯利（卡伦·伍德豪斯 Callum Woodhouse 饰）、玛格（黛西·沃特斯通 Daisy Waterstone 饰），以及一笔遗产。如今，这笔遗产已经被花的差不多了，孩子们亦在渐渐长大，问题日益凸显，使路易斯感到力不从心。
在巨大的压力之下，路易斯决定带领一家人远赴生活成本较小的希腊科孚岛定居，希望在那里开始新的生活。然而她的决定显然没有受到孩子们的欢迎和赞成，更何况何科孚岛甚至都没有通电。路易斯这个本想修复家庭关系的决定，却反而让兄弟姐妹们之间火药味十足。

The murder of a young boy in a small coastal town brings a media frenzy, which threatens to tear the community apart.

处在贝茨先生（布兰登•柯伊尔 Brendan Coyle 饰）受审一事阴霾中的唐顿庄园迎来了1919年的圣诞节。战争虽已过去，但影响仍在持续。房屋能被装饰一新，但唐顿人的心情却仍无法放晴。大小姐玛丽（米歇尔•道克瑞 Michelle Dockery 饰）觉得和理查德的婚姻不会幸福，但仍然决定继续；马修（丹•史蒂文斯 Dan Stevens 饰）仍对拉维尼娅的死感到愧疚；老爷（休•博内威利 Hugh Bonneville 饰）得知了玛丽不得不嫁给理查德的原因。尽管烦恼的事不断，但仍有好事传来。茜玻（杰西卡•布朗-芬德利 Jessica Brown-Findlay 饰）写信来告知了自己怀孕一事；被宣判死刑的贝茨因为证据不足改为了无期徒刑。新年晚会在贝茨的好消息中如期举行。新的一年即将来临，一切都在变化中，包括马修和玛丽的关系……
第三季将于2012年9月16日于当地时间首播。

The Great War rages across Europe, and not even the serene Yorkshire countryside is free from its effects. The men and women of Downton are doing their part both on the front lines and the home front, but the intensity of war only serves to inflame the more familiar passions: love, loss, blackmail, and betrayal.

Lord Robert Crawley and his family live a life of leisure, while a fleet of servants, including butler Carson, attend to their every need. But two events conspire to shake things up: the sinking of the Titanic, which claims Crawley's heirs, and the return of his valet, Bates. Since Crawley and Lady Cora have three daughters, his distant solicitor cousin, Matthew, becomes heir to the estate. With that, the scheming begins, since Thomas the footman views Bates as an interloper and Crawley's mother, Violet, feels the same way about Matthew's mother, Isobel.