Kristen Stewart is yet another Princess Diana in the trailer for Spencer
From Jackie director Pablo Larraín, Spencer is an "imagining" of Diana’s decision to leave Prince Charles

Following in the footsteps of The Crown’s two Princess Dianas (played by Emma Corrin in season four and Elizabeth Debicki in the upcoming season five), comes Spencer. From Jackie director Pablo Larrín, Spencer is “an imagining of what might have happened” during the Christmas celebration at the Queen’s Sandringham Estate when Princess Diana weighed divorcing Prince Charles. Coming this November 5th (a date that lives in infamy for the Guy-Fawkes-mask-wearing hackers the world over), Spencer promises to be another look inside the unknowable lives of the monarchy.
There’s very little to glean from the trailer outside of the film’s tone. With ghostly children’s choir singing Lou Reed’s ode to heroin, “Perfect Day,” Kristen Stewart’s Princess Diana frets about the house, twirls in her dance studio, and turns her head away from the press. It makes sense for Larrín to hone in on Diana’s isolation during these days, especially as she considered leaving the lap of luxury that became a prison. As a result, the trailer doesn’t make Sandringham Estate look like a very welcoming place.
Here’s the synopsis:
The marriage of Princess Diana and Prince Charles has long since grown cold. Though rumors of affairs and a divorce abound, peace is ordained for the Christmas festivities at the Queen’s Sandringham Estate. There’s eating and drinking, shooting and hunting. Diana knows the game. But this year, things will be profoundly different. Spencer is an imagining of what might have happened during those few fateful days.