The most popular series in PBS history, the UK show Downton Abbey, starring Maggie Smith, Hugh Bonneville, Laura Carmichael, and Jim Carter, will not be returning for its third season until January 2013, but the Internet is already buzzing with rumors about what will come to pass when the Julian Fellowes (Gosford Park) created series comes back to Masterpiece Classics.

The inclusion of Shirley MacLaine as Martha Levinson, Cora's (Elizabeth McGovern) mother (an addition that was announced in January), who will create a rivalry with Smith's Lady Violet, is just the tip of the iceberg. "There are some wonderful scenes between Maggie and Shirley MacLaine," Masterpiece executive producer Rebecca Eaton, told the Orlando Sentinel. This involves MacLaine "being as ditzy as ever" and "Maggie barely restraining her sneer in having to deal with this American."

Apart from new rivalries, there will also be a good dose of tragedy as the World War I-era Downton Abbey passes into the roaring '20s. "Somebody will be born, and somebody will die," said Eaton. "Somebody pretty key in the cast, unfortunately, is not going to make it," she told the newspaper.

In happier news, "Matthew and Mary do get married," Eaton confirmed.

Watch Season 3 of Downton Abbey starting in January 2013 on PBS.