Eric (O'Connell) is young criminal that is "starred up", that is, transferred from a juvenile prison to a high security adult prison, based on his violent nature. There he meets his father, Neville (Mendelsohn), who is serving a life sentence at this prison, and Oliver (Friend), a volunteer prison therapist who convinces Eric to join his therapy group. The lives of Eric and Neville will be forever altered.
This film features examples of:
- Blowing Smoke Rings: Eric is shown blowing smoke rings in his cell as part of a Time Passes Montage.
- Clothing Combat: The thug who jumps Eric in the showers hits him with a billiard ball in a sock, and then tries to strangle him with the sock.
- Groin Attack: When being transferred to solitary, Eric breaks loose and manages to clamp his jaw around the groin of one of the warders: putting him in an unusual bargaining position.
- Improvised Screwdriver: Eric creates a Sinister Shiv out of a toothbrush and a razor blade. The shiv doubles as a makeshift screwdriver, as he uses it to unscrew the light fitting in his cell in order to hide the weapon.
- Male Frontal Nudity: Jack O'Connell has two nude scenes: once when he is strip searched when he arrives at prison, and another when he is attacked in the showers.
- The Pen Is Mightier: During the standoff when the warders are trying to take him to solitary, Eric grabs the prison psychologist Baumer's pen and holds it to the eye of a warder. Baumer is able to talk him down and get his pen back.
- Prisons Are Gymnasiums: Many of the prisoners are showing working out to break the monotony of prison life. Eric's morning exercise routine includes doing push-ups on his knuckles.
- Reality Has No Soundtrack: No music score is used in the entire film, except for the scene where Neville escapes from his cell by hitting Selfy and during the end credits.
- Sinister Shiv: Eric's first act after arriving in prison is to construct himself a shiv out of a toothbrush and a razor blade. It also doubles as an Improvised Screwdriver.
- Situational Sexuality: Neville seems to have no issues with being homosexual when he is prison. And, as he has no hope of parole, he has resigned himself to being in a homosexual relationship for the foreseeable future.
- Spiteful Spit: When Eric seals himself in his cell, he spits at Haynes who is looking at him through the view slot. The gob is stopped by the perspex in the slot, however.
- Swirlie: Eric pisses off a drug dealer in his wing and he sends round some thugs who attempt to shove Eric's head down his unflushed toilet.
- Wardens Are Evil: Deputy Governor Haynes believes there is no point in attempting rehabilitate prisoners. With the aid of two warders, he delivers Eric a savage beating, and then attempts to murder him and make it look like a suicide. He is also in league with prison kingpin Dennis Spencer and smuggles in contraband for him.