I should have married a lazy, ugly man, says newly widowed, Jackie Kennedy (Natalie Portman), her accented words delivered with slow precision and breathy cadence in Jackie, Chilean director Pablo Larran's English-language debut.

Despite its potentially misleading title, this is not a biopic of of one of the worlds most iconic women but instead an intimate portrayal of the week following the assassination of John F Kennedy, through the grieving eyes of the former First Lady

The film is structured around an interview with an unnamed journalist (Billy Crudup) — based on the writer Theodore H. White’s interview for Life magazine — at the Kennedy home in Massachusetts, a week after the assassination.

Events from the past and present zip back and forth and include Jackie’s reflections on her early days in the White House, arranging her husband’s funeral and her controversial insistence that she walk with his casket to Arlington cemetery, amid fears about her security. Acutely aware of its potential, Jackie perceives this interview as an opportunity to define her husband’s legacy, as well as her own.

Portman has received a Bafta nomination for her performance and deservedly so. She is mesmerising. Jackie is rarely off screen and her beauty and presence has an intoxicating effect. Grief-stricken, she fights with poise and restraint, retaining her dignity in the aftermath of the fateful Dallas shooting and its ensuing political uncertainties.

Portman’s character is one of complexity and depth. She directs the interview with steeliness, ensuring that she has editorial control but in later scenes appears vulnerable, broken and lost, particularly when her immediate loss of status is apparent.

Only moments after holding her dead husband’s head in her lap — his splattered blood staining her face, pink suit and stockings — she has to stand in the background and watch Lyndon Johnson’s swearing-in ceremony aboard Air Force One. The inexorable speed at which the political machinery operates is shocking.

The gilded life of America’s political golden couple is presented in a recreation of Jackie’s 1962 televised tour of the White House, the purpose of which was to bring the White House to the people. “Objects and artefacts last longer than people,” Jackie tells her viewers, with unknowing irony.

But Jackie is also depicted as a woman on the edge. A confusing sequence sees her drinking, popping pills and dressing up in a number of clothes from her vast wardrobe, accompanied by Mica Levi’s jarring score.

John F Kennedy’s assassination was a seminal moment for many but the absence of closing notes means that there are no explanations of the key facts surrounding the events shown in the film. For those of us not alive at the time, Jackie’s blurring of fact and fiction ultimately falls short in depicting this defining episode in modern history.