Joaquin Phoenix’s Joker is discomfiting, physically as well as emotionally taxing (both, presumably, for Phoenix to go through and for an audience to watch) — and undeniably impressive. After shedding 52 pounds, Phoenix seems twisted up, his muscles and bones caving in just like his psyche. An unspecified condition that causes his character to break into bouts of painful laughter only exacerbates the effect. The rigor is in service of a movie without anything to say.

Though sad sack Arthur Fleck (Phoenix) dreams of being a stand-up comedian, he’s stuck in a thankless day job as a clown, twirling signs outside of stores and performing for sick children. At night, he returns to the apartment he shares with his mother (Frances Conroy), who has been writing letters to one Thomas Wayne (Brett Cullen) in the hopes that he might take pity upon them and offer them some financial help.

Arthur’s growing woes — the public funding providing him both therapy and medication is cut off, he’s fired from his job, and his ambitions at becoming a comic continue being stymied — reach a turning point when he commits an act of violence under pressure. He doesn’t feel torn about the murders he commits, but when every news outlet catches wind of the crime and clowns become the symbol of Gotham’s equivalent of Occupy Wall Street, he finally starts feeling some sense of recognition and validation. The transformation that ensues feels like watching the changing moods of a child, shyness giving way to tantrums, then sudden, frenetic dancing that barely seems under his control.

Phoenix excels in conveying the blurriness between control and chaos. Though it may be the fulfillment of his childhood dreams, watching Arthur do stand-up is easily one of the most painful scenes in the film. The set is sweaty, literally and metaphorically, as Arthur struggles to get his joke out as his laughter takes over, and as his expectant deliveries meet with stony silence. It’s not clear whether he’s managing not to break down out of sheer perseverance or the delusion that he’s doing well. Phoenix makes him easy to pity; director Todd Phillips makes that hard to maintain.

The magnetism of Phoenix’s performance wears off as Phillips reaches to find meaning. The works that the Hangover writer-director pulls from in order to paint a fresh portrait of an old character (specifically, Martin Scorsese’s The King of Comedy and Taxi Driver) traffic in the kinds of complex characters that Arthur is supposed to be, and succeed by exposing society’s ills. Joker, by contrast, paints a shallow portrait of a loner turned killer, who is, even by his own admission, removed from the anti-rich fury to which he becomes a symbol.

Even Phoenix — so compelling in The Master and You Were Never Really Here — can’t make Phillips’ kiddie pool seem deep, which goes a long way toward explaining how Robert De Niro, who appears in just a few scenes, almost steals the show. As Murray Franklin, the talk show host Arthur idolizes, De Niro is playing a neat reversal of his King of Comedy role, in which his character, the delusional Rupert Pupkin, takes his obsession with Jerry Lewis’ talk show host to an extreme. He also seems like the only actor in the film having fun, shimmying his shoulders and playing to the rafters, as a TV host should. He doesn’t have anything to prove, whereas the rest of the film feels hell-bent upon proving (with ultimately little success) that it’s not another comic book movie.

Other characters, like Zazie Beetz as the neighbor upon whom Arthur has a crush, Bill Camp and Shea Whigham as police officers, and Glenn Fleshler as a fellow clown, simply come and go. Though the people in his orbit give Arthur a little more dimension as an unreliable narrator (and give the film a little more dramatic cred), they fail to stop the movie’s descent into the exact territory it eschews. It’s called Joker, after all, and the Clown Prince wouldn’t exist without Batman. No amount of emulating 1970s cinema is enough to cover that up.

Joker’s ultimate shallowness becomes clearer as the movie progresses; the detailing is always superficial. A group of finance bros hassling Arthur breaks into a rendition of Stephen Sondheim’s “Send In the Clowns,” which, while broadly about the disappointments of life, doesn’t bear much relevance to the situation beyond containing the word “clown.” When Arthur makes the late realization that his life is a comedy, not a tragedy, the line lands with all the weight of a Hot Topic T-shirt slogan (and I say this as someone who used to covet those shirts). A scene in which Arthur defaces a sign so it says “Don’t Smile” instead of “Don’t Forget to Smile” is similarly destined for memes rather than any lasting, deeper analysis. There’s nothing to back it up.

The problem with Joker isn’t whether Arthur is a hero or a villain; the problem is that the film seems more concerned with proving its worth than saying anything meaningful. It’s beautifully shot and well-acted, and its most violent and shocking scenes land with visceral impact. But Phillips’ flashes of style are all in service of a grimdark image rather than a message about the haves and have-nots, or the treatment of mental illness, or any of the other real issues so easily within reach. It’s all show, and no substance.