The title of “Starred Up,” David Mackenzie’s brutal and boisterous new prison drama, refers to the status of its main character, Eric. Though he is legally still underage, Eric, played with method-actor inwardness and movie-star magnetism by Jack O’Connell, has been promoted to adult status in the British penal system.

It’s not hard to see why. Brawny and athletic, he looks less like a child than like a young bull, and his capacity for violence unnerves even some of the hardened older criminals in whose midst he finds himself.

One of them is his father, Neville (Ben Mendelsohn), a powerful inmate with a network of prisoners and guards at his beck and call. Eric and Neville’s relationship — full of rage, suspicion, shaky loyalty and blocked tenderness — is the dramatic heart of the movie, but Mackenzie (whose previous films include “Hallam Foe,” “Young Adam” and “Tonight You’re Mine”) is not one for sentimental tales of reconciliation.

“Starred Up,” based partly on screen­writer Jonathan Asser’s experiences as a prison volunteer, puts the setting in front of the characters and the plot. Though it is, finally, an affecting story of two damaged men bound by blood and something like love (and also a thrillerish catalog of double-crosses and shifting allegiances), it is, above all, a study in the patterns of chaos that govern penitentiary life.

The usual language of realism doesn’t quite apply to Mackenzie’s methods, which aim for visceral, nerve-jangling authenticity. He and cinematographer Michael McDonough let the camera run through the cellblock, a noisy, unbearably tense place where peace consists of the temporary absence of bloodshed.

“Starred Up” most resembles “A Prophet,” Jacques Audiard’s 2010 tour de force about power relations and male behavior in confinement. Like that movie, this one turns the complicated dynamic between a young prisoner and his problematic mentor into a ferocious psychodrama that locks you in and refuses to let you go.