The Summer of Slaughter is the name given to describe the events of one summer five years prior to the story, in which teen and youth crime and murder had gone up into extreme levels. Due to these incidents the British government made new laws to convict teenager for life sentences, giving the green light to the building of Furnace Penitentiary.
Since this period of time, distrust of teenage criminals became huge in the public eye. Personal stories of families being torn apart, the lack of sympathy by judges and juries and the threat of being sent to Furnace has only fuelled the movement. There was controversy over the opening of Furnace by human rights activists, but their stance was eventually shut down by the facts of the crimes and the general opinion of the public.
Even though the Summer of Slaughter has been blamed on gangs going to far, it has not been made clear why and how youth gangs and murders rose so quickly in that summer.
Thanks to the new laws, this system let many children fall to the extreme consequences. An example being of how Donovan, as a child in a case of domestic abuse, could have gotten a more lenient sentence, but due to the new law, was sent to Furnace regardless of association to any gang or not.
And as the premise of this story, this gave Warden Cross plenty of time to manipulate the system by framing his potential inmates into getting sent into Furnace.