The Demonata, book 2: Demon Thief
Darren Shan2005

A huge, jagged patch of light forms at the foot of my bed. Then a shape presses through. I'm too horrified to scream. It's a monster from my very worst nightmare. Pale red skin. Dark red eyes. No nose. Sharp, grey teeth. As it leans further forward I see a hole in the left side of its chest, and inside - dozens of tiny, hissing snakes. The monster frowns and stretches a hand towards me...

When Kernel Fleck's brother is stolen by demons, he must enter their universe in search of him. It is a place of magic, chaos and incredible danger. Kernel has three aims: learn to use magic, find his brother, stay alive.

But a heartless demon awaits him, and death has been foretold...