A trailer for the film shows Watts, 44, as Diana caught amid the pressures of fame after the former Sloane Ranger married her prince, gave birth to two sons, and then struggled to adhere to the confines of a measured life that seemed against her free-spirited soul. (Watch it below.)
From red carpets and designer ball gowns, to glamorous European yachts and the near-constant onslaught of paparazzi, the biopic focuses on the finals years of Diana's life as she sought new love away from Buckingham Palace. She died after a car crash in a Paris tunnel in August 1997, a tragedy that shocked the world as fans and royal watchers grieved with her sons, Prince William and Prince Harry.
Watts has it all down including Diana's layered short haircut, her long, spiky eyelashes, and her shy, head-down, eyes-up trademark smile, which along with her global charity work, earned her the nickname "Princess of Hearts."
The film is set to open in theaters on Sept. 20 in the U.K., but there is no official released date yet for the U.S.