McShera joins fellow “Downton Abbey” co-star Lily James, who will play the title role in the Kenneth Branagh-directed film.
“The Borgias’” Holliday Granger will play the other evil stepsister in the film. Cate Blanchett and “Games of Thrones” star Richard Madden are also on board as Lady Tremaine and Prince Charming, respectively.
Allison Shearmur, David Barron and Simon Kinbergare are producing the Disney adaptation set to be released on March 13, 2015. McShera will join the production in September after wrapping up season 4 of “Downton Abbey” in August.
Deadline.com was the first to break the story.