I'm deep beneath the streets of London, on the trail of a group of men who many would now call domestic terrorists.

Here it is.

These are the gunpowder plotters, the infamous Guy Fawkes and his fellow conspirators who, on the 5th of November 1605, tried to blow up a packed parliament in the name of their Catholic faith.

I think that this image shows just how sanitised this story has become.

Every year, much of Britain still celebrates Guy Fawkes night, his night on the 5th of November.

The Gunpowder plot has become a nice, family friendly party night with bonfires and fireworks and an engraving that's safe enough to be shown on the tube.

But this is not a safe story.

Back in 1605 when Guy Fawkes was caught, the ports were closed.

People panicked.

The state focussed all its attention on tracking down and executing the group of would be killers.

I want to investigate how these men reached the extreme, how they connected with others, and came to believe that the answer to their problems was wiping out the seat of power.

This was a dangerously radicalised network of men.

They were willing to risk everything to kill hundreds, if not thousands of people for their cause.

But what made them unite and plan this really monumental act of violence?

We tend to forget the names or even the existence of most of the plotters.

Yet even as children, they had connections to each other.

So to uncover the roots of their radicalisation, I'm starting this investigation by going back much earlier than most people do: to their childhoods.

Three of the future conspirators, John Wright and his brother Christopher Wright, as well as Guy Fawkes, all went to the same school...growing up in the city of York.