Derek Landy 
Skulduggery Pleasant: The Faceless Ones 

Valkyrie screamed, sprinting toward Skulduggery. He looked up and reached out to her, but it was too late.f you’ve read the other Skulduggery books by Derek Landy (and you really should have read them by now), you’ve seen it all before: Some bad guy wants to bring about the end of the world, and Skulduggery and Valkyrie fight valiantly to stop it from happening. A few people get hurt, sure, but everything’s all right in the end.Well, not this time.