A group of twenty young men will run a marathon for the first time in their lives, but they're all prisoners, so the course and scenery stays behind bars.
Every step of the endurance event is made inside the barbed wire of Christchurch Men's Prison.
The course is made up of a 2.2 kilometre loop.
Inmates will have to run it 19 times to complete the marathon distance.
Prison staff are joining the inmates on the track.
The prisoners are all in the youth unit, aged between 17 and 20, and for some the experience has been life changing.
The prison marathon is a first for New Zealand and will start at dawn on January 5, 2018.