A Hollywood sneak peek of series three reveals fireworks between Downton Abbey matriarchs Dame Maggie Smith and newcomer Shirley MacLaine.
The aristocratic Crawley family endures a financial crisis and despite the engagement of Matthew and Mary at the end of last season, all is not well with the pair, portrayed by Dan Stevens and Michelle Dockery.
PBS showed brief clips from next season to the Television Critics Association before a panel discussion with cast members and producers of the international hit.
They took a break from filming in London to meet reporters in Beverly Hills, California.
Downton Abbey returns in September in the UK and next January on PBS.
Their visit followed a strong showing by Downton Abbey in Thursday's Emmy nominations with 16 bids, including best drama series.
In one scene shared by PBS, Hugh Bonneville's Robert Crawley, also known as Lord Grantham, is shown confessing to his wealthy American wife Cora (Elizabeth McGovern) about an investment gone wrong.
"Has some of my fortune been lost?" she asks.
"Almost all," he replies, tearfully.
Matthew and Mary, who travelled a rocky road to what looked like blissful marriage, are shown in an angry confrontation in which she accuses him of disloyalty to the family.