The Demonata, book 1: Lord LossDarren Shan2005

The door feels red hot, as though a fire is burning behind it. I press an ear to the wood - but there's no crackle. No smoke. Just deep, heavy breathing... And a curious dripping sound. My hand's on the door knob. Inside the room, somebody giggles - low, throaty, sadistic. There's a ripping sound, followed by snaps and crunches. My hand turns. The door opens. Hell is revealed.

When Grubbs Grady first encounters Lord Loss and his evil minions, he learns three things: the world is vicious, magic is possible, demons are real.

He thinks that he will never again witness such a terrible night of death and darkness.

...He is wrong.