Getty From the small screen to the big screen, Mckenna Grace and Paul Walter Hauser are going to star in another project together! The 19-year-old actress and the 39-year-old Emmy-winning actor are starring in the upcoming live-action Scooby-Doo series, and it was just announced they will reunite for a movie. According to Deadline, Mckenna and Paul will star with Louis Partridge in the revisionist romantic comedy The Official Mistress, which is about the final days of the French monarchy.