When a body turns up in mysterious circumstances, in the Scottish Highlands, there are very few clues to the identity of the deceased man: blue overalls and a numbered tattoo on his ankle. Shortly afterwards, another body turns up in the West Country, once again in unexplained circumstances. The dead man was wearing blue overalls and had a numbered tattoo on his ankle. When further violent incidents occur, in a range of locations across the country, Scotland Yard realise they are dealing with a dangerous criminal organisation. The roots of the organisation go back to the 1950s when it was a benign group of peace protesters. But over the years, something has gone horribly wrong.