You probably saw on our programme yesterday that a teenaged boy was found guilty of the murder of 15 year old Kiyan Prince last May.
Hannad Hasan took Kiyan's life with a penknife, and left a family destroyed...
For the last year, London Tonight has been given unprecedented access to Kiyan's relatives. To his mother and father, and even his younger sister, as they tackle life without him.
Despite his pain, Kiyan's dad Mark is determined to do something more positive. He's decided that the only way to make sense of his loss, is to make sense of what's happening on our streets. So he's taken his fight to the frontline. He's working with young people to raise their awareness of what happens when you carry a knife, and when you use it.
And during a film to be shown on London Tonight at six o'clock, we witness his courage in action.
We follow him as he talks to the young boys drawn into a life of crime, we join him as he struggles to cope with the pressure of THREE murder trials, and we help him create a campaign that we hope will make Kiyan's life matter.
It's a remarkable story, and one that we should all take courage, and inspiration from.
Make an appointment to see "Put the Knives N Guns Down" here on ITV1 at 6.