By Nicole Sperling
July 10, 2009 at 04:21 AM EDT

In a matter of weeks, actress Hope Davis will transform herself from Annette — the upper-class wife and mother who spars on stage with Jeff Daniels, Marcia Gay Harden, and James Gandolfini eight shows a week in the Tony Award-winning Broadway play God of Carnage — into Hillary Clinton for HBO Films’ political drama The Special Relationship for British director Richard Loncraine (Wimbledon). She was just asked Monday to step into the role after Julianne Moore had to bow out due to a scheduling conflict. Now, Davis is tasked with embodying our current Secretary of State during her less glamorous years as First Lady to Bill Clinton (played by Dennis Quaid) during the Monica Lewinsky affair.

So how does the award-winning actress plan to hastily prepare? Through lots of audio tapes, lots of books, and a trusty wig. “With something like this, you can’t spend all your time worrying about what you sound like, that you’re not doing the storytelling part,” Davis tells EW, while on her way to yet another live show of Carnage. “That has to come first.”

While the title A Special Relationship refers to the friendship between two heads of state, U.S. President Bill Clinton and British Prime Minister Tony Blair (to be played for the third time by actor Michael Sheen), the film, from screenwriter Peter Morgan (The Queen), also imagines what went on behind closed doors between the Clintons during the Lewinsky affair. And it’s something Davis can relate to. “Almost every woman in the world has been in that position — it was a long time ago in my life — where the person that you trusted looks at you and says, ‘I have an admission to make.’ It’s a moment we’ve all lived through.” 

Davis will be flying to London on Sunday to meet Quaid and Loncraine and to do a script read-through. Production will begin July 20 and Davis will join the cast in the beginning of August.