The Furnace Series are a collection of young adult science fiction novels, written by Alexander Gordon Smith. The novels feature the Furnace Penitentiary, the worlds most secure prison for young offenders.
The Furnace is buried one mile beneath the surface of the earth with only one way in, and no way out. Once you have arrived at Furnace, you never leave, there until you die. Dying doesn't often happen from old age either with sadistic guards, bloodthirsty gangs, and something a whole lot worse.