Natalie Dormer, Ed Speleers to star in 'The Lady' for BritBox, ITV

March 20 (UPI) -- Game of Thrones and Elementary actress Natalie Dormer has signed on to play Sarah Ferguson, Duchess of York, in the new BritBox and ITV series, The Lady.

How to Have Sex alum Mia McKenna-Bruce will play Sarah's former royal aide-turned-murderer Jane Andrews and Ed Speleers from Downton Abbey and Outlander has been cast as Thomas Cressman, Andrews' businessman boyfriend and eventual stabbing victim.

The cast for the four-part drama -- which is set in the late 1990s and early 2000s -- will also include Philip Glenister, Claire Skinner, Laura Aikman, Ophelia Lovibond, Mark Stanley, Daniel Ryan and Sean Teale.

"The Lady charts the rise and fall of former royal dresser Jane Andrews, whose rags to riches fairy tale fell apart when she was convicted of murder. Once a young working-class girl, Jane answered an advertisement in a magazine and to the astonishment of her friends and family, became the Duchess of York's dresser at Buckingham Palace," the networks said in press release Wednesday.

"Moving amongst the highest social circles in Britain, Jane managed to secure a place in the upper-classes, only to lose her job with the Duchess after nine years of service," the summary added. "Still reeling from her fall from grace, Jane went on to meet charismatic businessman Thomas Cressman and fell deeply in love. Soon cracks began to develop in the romance Jane had pinned all her hopes on, with disastrous consequences."

Ferguson is the ex-wife of Prince Andrew, King Charles' younger brother.