Tonight, Campbell Live goes inside a prison.
In the two decades from 1992, New Zealand's prison population has doubled.
Our imprisonment rate is now among the highest in the Western world – higher than Australia, Canada and the UK, twice that of France and Germany.
Sentences have been getting longer too. But they eventually still get out, and a quarter of them are back inside within a year.
The Minister of Corrections has demanded re-offending rates are reduced. But how?
Last Thursday, Campbell Live cameraman Cam Williams and John Campbell, went inside Rimutaka Prison.
To protect their victims, they couldn't identify prisoners or talk about their crimes.
But they could ask inmates, the people who work with them and the Corrections boss charged with reducing their re-offending how to keep prisoners out when they're released.
Watch the video for the full report.