The Lost Colony by Eoin Colfer

Big human haters, they are (thankfully) stuck in Limbo, a place that exists outside of time and space. But now demons are materialising on Earth at random. This won’t be pretty . . .

Artemis is determined to save the day (I know, everyone’s shocked). Can he somehow help the demons, and avert the carnage and chaos of a human-demon war?

He’s not the only one on their trail, though. Meet Minerva Paradizo – ruthless child genius, and not quite so demon-friendly.