The hit British period drama “Downton Abbey” returns Sunday night for its third season on American airwaves. The latest season promises to bring plenty of surprises for the show's characters.

One of the most exciting new changes in the show’s third season is the introduction of Shirley MacLaine as Martha Levinson, the American mother of Lord Grantham’s wife, Lady Cora.

Hugh Bonneville, who plays Lord Grantham, recently spoke with Zap2it about his character’s interaction with his mother-in-law. Based on Bonneville’s descriptions, Martha Levinson should be an excellent addition to the “Downton Abbey” family.

"Any married man who hears the words, 'Your mother-in-law is coming to stay,' that does strike an arrow of dread into the heart," Bonneville said. "In character terms, she's the mother of her daughter. Cora, relative to a character like Robert, is a complete free spirit. Martha Levinson is very much the mother of her daughter. She has forward-thinking values, relative to the Downton stock."

As for MacLaine herself, she certainly seems equally excited to be making an appearance in the BBC drama. MacLaine spoke with the Salt Lake Tribune of Utah about her appearances on “Downton Abbey,” describing her back-and-forth with cast member Maggie Smith, who plays Violet Crawley, Dowager Countess of Grantham.

“I thought the best course of action in going toe-to-toe with Maggie would be a sense of American expressive feeling,” MacLaine said. She went on to tell the paper that she and Smith bonded on the set.

“The day we shot in the church, when we’re all done up in our white fur, we sat there all day,” MacLaine told the Salt Lake Tribune. “And Maggie and I don’t like to get up and walk around a lot anymore. So we sat and we reminisced about life and lovers and the business and directors. That was really interesting and so much fun.”

Be sure to catch “Downton Abbey” as it returns to PBS Sunday at 9 p.m. EST.