Furnace Pack Pack by Alexander Gordon Smith (author)

Beneath heaven is hell. Beneath hell is Furnace Penitentiary – the world’s most secure prison for young offenders. It’s buried a mile beneath the earth’s surface. Once in, you’re here until you die… and for most of the inmates that doesn’t take long. Now Alex is caged in the darkness at the bottom of the world. But death is the least of his worries. The prison is a place of pure evil, where creatures in gas masks stalk the corridors at night; where giants drag screaming inmates into shadows; where deformed beasts howl from blood-drenched tunnels. Can Alex break out of Furnace before they make a monster out of him?

“Furnace is hotter than hell and twice as much fun! Sign me up for a life sentence!” Darren Shan