Mark O’Connor has quickly become something of a veteran of Irish social realism and bleak crime dramas that focus on disenfranchised characters and the underbelly of society. In Amongst The Wolves, he returns to the street-level grit that defined Cardboard Gangsters and King of the Travellers, inviting his audience into the bruised and blistered world of Ireland’s margins. This time, the scars are not only social but psychological, as the film weaves a narrative of PTSD, homelessness, and the violent inheritance of trauma in a contemporary Dublin that feels more battlefield than city. O’Connor does this well, but ever since Love/Hate in 2010, the amount of Irish shows and films about men navigating a drug-riddled criminal underworld is starting to feel oversaturated, and despite shining moments, Amongst The Wolves doesn’t feel as fresh as it could.

Danny (Luke McQuillan, who also co-wrote the screenplay) is a war veteran returned from Afghanistan and living in a tent by the canal, estranged from his family and haunted by memories that refuse to fade. His face carries the weight of everything he's lost: home, marriage, custody of his son, and possibly his grasp on peace. McQuillan plays Danny with a sedated, hollowed-out intensity that fits the character’s slow-burning unravel. His performance simmers, is never showy, and becomes most affecting in the quiet, tentative moments with his young son, or with Will (Daniel Fee), a teenage drug runner who becomes a surrogate son of sorts.

The plot, like Danny’s psyche, is fractured: a mix of kitchen sink realism, social critique, and gangland revenge thriller. It occasionally loses its footing under the weight of competing themes as O’Connor's script howls at a dozen things at once: austerity, broken institutions, toxic masculinity, Ireland’s treatment of its veterans and its poor. At times, the script strains under its own fury, but its anger is righteous, and its commitment to realism is bracing. It’s in the screenplay’s quieter, human moments that O’Connor’s social observation combines with pathos to provide a gutpunch. An opening that sees Danny humiliated and attacked by a group of men while trying to sleep along the canal shows the casual cruelty and dehumanisation homeless people face. When Kate speaks about losing her homeless brother to addiction, she quotes his reason for using heroin; “It makes the concrete softer.” These small moments of heartbreak are natural and stirring, a signal to fix broken systems and extend compassion.

There are lost opportunities for more of this. For example, exploring the experiences of the women adjacent to these broken men; or exploring Danny’s decision to go to Afghanistan and the contrast between promises of heroism, camaraderie and social respect offered by the army and the reality of a cruel world defined by male violence. As the action ramps up, it’s clear that like war, there’s no glamour in this revenge and no neat catharsis. Attempts to do something good can get skewed and warped when the social contract breaks down. Introducing the idea of war and PTSD without exploring them feels like a missed chance, especially as McQuillan seems up to the task of performing this type of inner conflict.

Aidan Gillen’s Power, the local gang leader, is less effective. Gillen leans into the well-worn archetype of the sadistic Dublin gangster with a familiar twitch of menace that Gillen himself has become known for. While he exudes control and always has screen presence, his character feels written from the outside in - all threat, little depth. His villainy peaks in a grim, gratuitous act of animal cruelty meant to underline his depravity, but which instead plays as a heavy-handed and well worn trope, in a film that otherwise strives for moral complexity.

Louise Bourke as Kate, a charity worker with her own grief to bear, offers one of the more touching subplots, and her scenes with Danny hint at a potential for human connection, however fleeting. Fee’s performance as Will adds heart to the story’s core. In his vulnerability and recklessness, we get a glimpse of Danny’s own younger self, still stranded in a war zone no longer defined by geography.

Visually, the film is a triumph. Ignas Langalis’ cinematography paints Dublin in harsh greys and toxic greens, all rain-slicked pavements and flickering streetlights. The camera captures both the ugliness and unlikely poetry of the city’s forgotten corners: graffiti-smeared underpasses, quiet canals, emergency shelters. In the film’s best visual moments, the city feels not only lived-in but turned inside out, echoing Danny’s internal decay.

Amongst the Wolves ultimately backs itself into a corner where the only way out is blood. Its final act embraces the genre’s conventions, trading emotional ambiguity for narrative closure. O’Connor has a talent for menace, fear and suspense and plays with them well, though the beats in the final act feel overly familiar and fit too tidily into a revenge fantasy, when the messy indignity of more realistic action could have made the film feel more emotionally complex. Side characters verge on stereotypes, the plot becomes overburdened, and the ending doesn’t quite land. But Amongst the Wolves is the kind of flawed, feral indie that claws its way under your skin. The shining moments demand that it be witnessed in its flaws, just like its characters.

At his best, O’Connor provides a loud and clear voice in Irish cinema, chronicling the country not through myth or melodrama, but through mud, bruises, and the quiet dignity of those pushed to the edges. One feels that if he could free his work from the familiar trappings of the genre, his work could really sing.

• In cinemas now.