“YOU WERE NEVER REALLY HERE ”

****

(R, 1:30)

A journey to the deepest levels of the dark side, “You Were Never Really Here” is an art-house crime thriller that succeeds on every technical and creative level.

From its soul-searing cinematography to its breathtaking use of music through the haunted lead performance, it bursts at the seams with 90 minutes of genius moments. Writer/director Lynne Ramsay has created the kind of work that brings viewers into a stunned silence, grappling with unknown, instinctive emotions.

Joaquin Phoenix won the best actor award at last year’s Cannes Film Festival for what is surely the pinnacle work of his career. He delivers a phenomenal, fearless performance as Joe, a battle-hardened veteran turned undercover goon for a shady New York private detective. He suffers PTSD from his time in the Mideast, but, as we soon learn, long before that he carried mental damage from his childhood.

When we meet him, he’s in a suicidal funk in the messy home he shares with his declining mother (Judith Roberts), performing a suffocating form of self-torture. When his mom calls to him, he goes downstairs to attentively help the only significant person in his life.

Joe’s specialty is rescuing young girls from sex slavery rings. His grisly job gives him meaning in a world that disgusts him, shifting his self-destructive impulses into punishing men who deserve the pain more. He is a knight in very bloody armor, or to be accurate, shabby work pants, a mountain-man beard and face-cloaking hoodies.

His usual smash-and-grab rescue involves a ball-peen hammer, a stranger’s fractured skull and a traumatized child carried away on his meaty shoulder. Phoenix gives this lonely, sad contract killer palpable emotion without a wasted gesture or overdone look. His Joe is deeply abnormal, at times genuinely frightening, yet completely understandable. While no one will displace Robert De Niro’s similar character in “Taxi Driver,” Joe surely brings Phoenix up on equal footing.

His new client is Albert Votto, a New York senator. According to an anonymous text, his daughter Nina (Ekaterina Samsonov) has been kidnapped and forced to work in a Manhattan brothel. Votto, who doesn’t want to get the police involved, calls Joe into his office for a meeting. “They said you were brutal,” Votto says. “I can be,” Joe replies. “I want you to hurt them,” says Votto.

When Joe sets out to do his demolition work, he finds himself in a more destructive conflict than he has ever fought, facing ruthless power while trying to humanize his own inner demons. It’s hard not to see this sociopath as a would-be savior.

Ramsay makes a great spectacle of this pulp material without resorting to commonplace action sequences. Most of the killing happens off-screen or at a distance, while cinematographer Thomas Townend turns its splattered aftermath into visual poetry of green, red and black. Ramsay finds a perfect, unexpected shot for every trip down a menacing hallway, every eruption of savagery.

But there’s much more to the film than its imagery. Ramsay won the Cannes prize for best screenplay, implicitly drawing us into Joe’s shaken mentality as he tries to execute an act of redeeming sacrifice and grace.

The film is filled with paradoxical, ambiguous acts and darkness so close to its characters that it threatens to envelop them. Even the asides — the “Do Not Disturb” tag on a hotel door — carry insidious irony. Jonny Greenwood’s hellish modernist musical score conveys additional layers of menace.

The plot has surreal twists that become plausible once we catch our breath. Joe’s chaotic world takes repeated stress tests in the last act, leading to a twisted coda where dueling delusions wrestle up to the credits.

It’s not just a great film, it’s essential.