Kenneth Bulmer 
Demons [EPUB ebook] 

Gigantic were The Demons who terrorized the underground kingdom of Archon. Yet, who were they? Whence came their fantastic power? Why did they wage ruthless and relentless war against Archon? These were questions to which there was no answer until Stead arrived in Archon, apparently from nowhere.Only after he had been a Forager for some months, and had experienced the spine-chilling dangers of The Outside did Stead arrive at a solution. Even then he had a difficult task convincing the Controllers, who, for generations, had insulated themselves against the harsh truth. Only those who had actually seen The Outside – the Foragers, Soldiers and Workers – could properly understand.