Following the destruction of Castle Underock, Dark has set off alone in the world to find answers to his questions: who is he, why was he imprisoned in a hole for his entire life, and why can he mimic any ability he sees? But the realm is in turmoil as the ten barons argue over who shall replace the deposed king, and humanity is now terrified by the discovery that some of the Old World monsters aren't as extinct as they'd believed. And someone is infuriated by the boy and his monster friends, sending an assassin to hunt him down and kill him. She is The Girl With The Knives, and she has a special ability of her own: she never misses. Dark's exploration of the chaotic world of humans is cut short when he discovers more Old World creatures in hiding, the assassin closes in, the boy is changing into something far more monstrous than his friends, and humanity unleashes even more powerful weapons that will set the whole world on fire unless Dark and the Nightlings stop them. But this is war, and there will be casualties.