London in 1856. Karl Marx is living in exile in the British capital. One day, "Mohr", as Marx is called by his friends, meets the 13-year old worker′s son Joe. The boy works every day for twelve hours in a spinning mill and even has to work night shifts although that violates current rules. Marx tries to end the illegal activities of the spinning mill owner and one night shows up at the mill together with an inspector. But his foray is undermined by a robbery by the rebellious raven gang that is led by Joe′s brother Billy. The spinning mill owner of course takes this chance to blame his young workers for the theft. But Marx is not let astray and does not stop to fight against child labour. Furthermore, he tries to get the members of the raven gang back on the straight and narrow – with success.