The functioning of the Mountjoy Campus is interrupted by an extremely violent prisoner who is being moved to a specially-modified cell. While the prison is dangerously close to overcrowding, James, a prisoner, is hoping for a transfer to the Training Unit while the massive drug problem in the prison is out of control.

With screened visits in place, staff in Mountjoy West are steeling themselves for backlash from inmates. While a prisoner, Paul is hoping to make it to the Training Unit, an officer is trying to use sport as a way of motivating prisoners. With the jail almost full, tensions are at boiling point and there will be violent consequences for both prisoners and staff.

As the prison hits maximum capacity, the staff try managing tensions and the acute drug problem. The Training Unit FC begins the soccer tournament hoping to make it to the finals. Meanwhile, Conor is in trouble over his temporary release for a college course. Over in Mountjoy West, Paul faces a setback to his Training Unit ambitions and begins to slip from the path he has laid out for himself.

The capacity crisis in Mountjoy Prison comes to an end, but a prisoner's death poses complications and heartache. In the main prison, an emotional Officer Kelly prepares for his retirement from the job after 30 years of service. Over in Mountjoy West, staff have to contend with an unruly prisoner and a dirty protest in one of the cells.