There Is a club that no high school principal in the USA wants to join, but they are all incredibly grateful that its there. Because in the event of the worst possible scenario happening, they will need it

The 'Principal Recovery Network' is made up of school leaders who have lived through the horror of a shooting in their hallways and classrooms. And in the hours after an incident they are on the phone helping the next school principal through their trauma

Sam Walker moved her family from Manchester to Arizona seven years ago and she still can't get used to her kids going through regular lockdown drills so they know what to do if their school is attacked

Sam meets some of the principals who have been through it and have come together to offer support - and now activism.

Presenter: Sam Walker Production: Sam Walker and Richard McIlroy Image: Frank DeAngelis, the former Principal of Columbine High School