After John F Kennedy's funeral, a reporter (Billy Crudup) comes to the palatial home of his widow Jackie (Natalie Portman). He's here to tell his readers what's going through her mind and how she feels, but she's a little bit more combative and controlling of the message, possibly more hardened and cynical after her experience of politics and the media in the aftermath.

If there's any theme in Jackie, it's about the evolution from a woman many dismissed as a fashionable dolly bird best known for buying stylish trinkets into a mature and wily figure made brittle even while she tries to mourn.

As she tells her stories, the film goes back and forth in time to paint the picture of the graceful but slightly glacial girl who found herself in such a position of power.

In the early days she tried to endear herself to the American people by staging a series of televised tours around the White House showing off her restoration of classic artworks and fixtures, a process that later on morphs into a decision to fly all the way back to Washington with her husband's brains still drying on her iconic pink outfit so the world can appreciate the weight of what's happened.

And all the while, the machinations of governmental continuity and the sadness of opportunities lost goes on in a mad scramble around her, from Bobby Kennedy (Peter Sarsgaard) trying to contain the looming political crisis and the rushed swearing in of Lyndon B Johnson (John Carroll Lynch) on Air Force One and Jackie's own determination to do her husband's legacy justice with his burial.

An off-kilter soundtrack of pained, dramatic violins elevates the proceedings, making it sound at times like a prestige horror movie and elevating the story off the page just as much as the fractured timeline does.

But there are a couple of missteps too – one being the excess of ideas it sometimes feels like it's cramming in. John Hurt as Jackie's priest and confidant is just one member of an amazing cast but it feels like the movie's just trying to apply another level it doesn't need.

Despite so many great performers, all eyes are (and should be) on Portman as the First Lady. Not many people alive today have much experience of what Kennedy really moved or talked like, but you can see the command Portman has over the portrayal.

Even when it seems to dip over into caricature – like in the televised tours – it's only because Kennedy's natural accent and comportment come across more strongly. You expect the tenderness, but it's the power that exudes from such a slight, pinched frame that really surprises you.

And while it focuses on the personal and political it's also something of a feminist story, Jackie having to fight back (while enmeshed in the worst possible circumstances) against the forces who want to sit her down and shut her up and do the big boy's work.