When Oprah Winfrey’s interview of Prince Harry and Meghan Markle aired back in March, I joked with a friend that it represented the lowest point in Anglo-American relations since the War of 1812. Between Harry and Meghan’s withdrawal from the family, their revelations about its internal racism, and the alleged connections between Prince Andrew and Jeffrey Epstein, the grace and mystique that made the royals a fascination stateside has entered a palpable state of decline.

All of this controversy has set the stage perfectly for Pablo Larraín’s Spencer, which does everything in its power to strip the royal family of their majesty and reveal them as both repressed and repressive, a moribund institution that justifies its intransigence as a mere upholding of tradition. While clothes may play a central role in Spencer’s plot (Princess Diana chafes against the rigid wardrobe schedule set for her), this isn’t a costume drama. It’s a psychological horror film where the central character tries to escape both the voices in her head and the voices, largely unheard but their influence felt, that try to dictate what’s best for her and her two children. When it works, it’s startling and affecting. When it doesn’t, it’s shallow and histrionic.

Spencer takes place during Christmas 1991, at which point Prince Charles (Jack Farthing) and Princess Diana (Kristen Stewart) are still married despite Charles’ affair with Camilla Parker-Bowles (Emma Darwall-Smith) being an open secret. The film goes to lengths to establish Diana as a rebel and a true princess of the people – she commiserates with and confides in Darren McGrady (Sean Harris), the Royal Head Chef, as well as Maggie (Sally Hawkins), her dresser, while avoiding and ignoring every royal who isn’t one her sons, Prince William (Jack Nielen) and Prince Harry (Freddie Spry). She also runs afoul of Alistair Gregory (Timothy Spall), a sort of royal concierge whose job it is to make sure everyone is at dinner on time and wearing the right clothes, a jowly personification of the expectations unwillingly thrust upon the future queen consort.

Most of the action unfolds at the Sandringham Estate, one of the queen’s sprawling country homes that, for the purposes of this film, may as well be the infamous, haunted Manderaly of Alfred Hitchcock’s Rebecca. Larraín and cinematographer Claire Mathon go to great lengths to make royal life seem as unpleasant as possible, shooting Diana tightly and following her with a wobbly camera that disorients the viewer to the point of anxiety. Johnny Greenwood’s score does its fair share to keep viewers on edge as well — the scratchy, droning strings that accompany Diana as she runs across the Sandringham’s mist covered lawn bring to mind pastoral horror films like The Witch and Midsommar, while the moody horns add an air of noir-ish menace.

The first two thirds or so of Spencer are an effective portrait of an unraveling mind. Diana is clearly unwell – she binges, she purges, she cuts, and she even begins to see the ghost of Anne Boleyn, who was herself the victim of the unfaithful Henry VIII. She also becomes obsessed with her childhood home, located just over the hill from Sandringham, boarded up and behind a ring of barbed wire, eventually taking it upon herself to break into the rickety, decaying building in an attempt to reclaim some sense of innocence and happiness. This return triggers a montage of childhood memories and a series of scenes in which Diana imagines herself dancing defiantly both as a child and an adult, culminating in her tearing off the pearl necklace Charles bought her, a final declaration of freedom.

This is where the film lost me. For all of the interiority granted Diana, we get precious little insight into why, exactly, the Windsors and the people around them want to maintain the traditions that Diana finds so stifling; it also ignores the fact that her allegedly perfect childhood was the product of the very system she seems to hold in contempt (her father was a viscount, and their house was literally leased from the queen). Instead, she’s portrayed as some sort of tortured free spirit who later confesses to Maggie that she’d rather be middle class so she could enjoy Les Miserables and KFC in piece, which is as trite and condescending an attempt to make an exorbitantly rich person “relatable” as I’ve ever seen. I don’t want to sound unsympathetic to Diana’s plight – I can’t imagine the toll being trapped in a loveless marriage and then pretending that everything is perfectly okay must take on a person. But rather than treat her like the complicated and multidimensional public figure that she was, Larraín and screenwriter Steven Knight try to turn her into nothing more than self-liberating Rapunzel, with the Windsors playing the role of the one-dimensionally evil stepmother.

Stewart has been lauded as an Oscar contender for her performance, but I have to confess that I found her Diana one-note and overwrought. Every other line is delivered as she sheepishly looks off to the side, juts out her chin, and clenches her teeth, a move that calls to mind a petulant teenager rather than a rightfully indignant icon. If there is one scene where she shines through, it’s when she plays a game with William and Harry where they pretend to be soldiers and “order” each other to tell the truth. Here, her sense of motherly warmth and playfulness radiates, even though the flickering candlelight and her pale complexion call to mind a preemptive séance rather than a lighthearted childhood game. In this same scene, Harry asks William if he wants to be king, and William answers honestly – it doesn’t matter what he wants, because he has no choice. It’s a small moment, but one that helps illustrate why Diana is both disenchanted and horrified by her life – she too, has no choice but to play the role both the public and the royal family expect her to play.

And yet, prior to the events of this film, she did, in fact, choose to marry Charles and become part of a family she now despises. Why that was ever appealing to her in the first place, and how it slowly began to morph into the living hell Larraín and Knight insist it was, is a crucial story that this film sadly leaves unexplored.