Beneath heaven is hell. Beneath hell is Furnace.

When thirteen-year-old Alex is framed for murder, his life changes for ever. Now he is an inmate in the Furnace Penitentiary - the toughest prison in the world for young offenders. A vast building sunk deep into the ground, there’s one way in and no way out.

But rowdy inmates and sadistic guards are the least of Alex’s problems. Every night an inmate is taken from his cell by guards and returned the next morning changed. Where are they taken and why are they returned covered with scars, acting as though they are not quite human? In a desperate bid for freedom Alex discovers a horrifying truth - that the Furnace Penitentiary is a place of pure evil, a place where cruel experiments take place every day, where inmates are guinea pigs, where monsters make monsters, and where death is the least of your worries.