It was the occasional smell of weed which made detectives suspicious at first.
Then a mystery delivery alerted police to the former nuclear bunker in the middle of the English countryside.
But when detectives mounted a raid on the underground fortress, they had no idea if they could get through the atomic blast doors. And when they did - what would they find?
What followed was a moment of high-tension as the team had just seconds to catch an organised crime group in the act.
And detectives uncovered a unique drugs factory built on a scale not seen before in England.
But this is no crime caper. Soon police saw for themselves the dark side of drugs production.
