“Game of Thrones” thesp Richard Madden is set to star opposite Rebecca Hall in the period piece “A Promise.”Patrice Leconte is helming from a script he co-wrote with Jerome Tonnerre. Story is set during pre-World War I Germany in which a young engineer, played by Madden, goes to work for a wealthy older man and ends up falling for the benefactor’s wife, played by Hall. The war forces them to part and the relationship is put on hold until the two meet nine years later. Olivier Delbosc and Marc Missonnier will produce through Fidelite Films. Production is set to start at the end of the year. The part marks one of Madden’s first leading roles since his breakout as Robb Stark in HBO’s “Game of Thrones.” The WME- and Troika-repped Madden is currently filming “Game of Thrones” and will move into “A Promise” as soon as the skein wraps filming on its third season later this year.