A shank attack on three prison guards, purportedly as revenge over an incident involving notorious gangster Joshua Masters, shows the dangers of a job managing some of New Zealand's most dangerous people. Sam Hurley reports.

Two of a trio of inmates who carried out a brutal revenge attack on a group of prison guards will serve even more time behind bars.

The Herald can also reveal the three guards they


Assaults on guards climbs steadily in recent years

Guards accused of falling foul of the law