[3] The film revolves around the life and behaviors of a mentally distressed young man called "Nitram" (based on Martin Bryant), and the events leading to his involvement in the 1996 Port Arthur massacre in Tasmania.

It received widespread critical acclaim for Kurzel's direction and the cast's performances (particularly Jones and Judy Davis), although the film sparked controversy in Tasmania.

The film begins with real archive news footage from 1979 of a 12-year-old Martin Bryant being interviewed in a burns unit of a hospital after playing with fireworks.

The two quickly become friends, and Helen buys him a car, despite Nitram not having a driver's licence and exhibiting a dangerous habit of grabbing the steering wheel when the two are driving.

Nitram becomes increasingly frustrated with life at home and tells his parents he is moving in with Helen, who permits him to stay in a spare room but insists that he get rid of his air rifle as it upsets her.

After he shows up to his father's funeral dressed in an electric blue suit and hat, Nitram's mother refuses to let him attend, fearing he will embarrass her.

The website's consensus reads, "Nitram asks viewers to face a gut-wrenchingly grim moment in Australian history—but rewards that effort with a gripping, well-acted character study.

Kelly Spaulding, mayor of the Tasman Council, which includes Port Arthur, condemned the choice to make the film.

The Alannah and Madeline Foundation, which was established by Walter Mikac, whose wife and two young daughters were murdered in the Port Arthur massacre, released a statement also condemning the choice to produce the film.

Other state politicians including Brian Mitchell, federal member for Lyons, and Rebecca White, Leader of the Opposition, expressed concern.