The Dark Age is a trilogy by Mark Chadbourn set around the beginning of the third millennium. While the previous series was a clear fantasy story, this has strings of gothic horror and existentialism woven into it.
The three books are:
Although not a direct sequel to The Age of Misrule, it is a continuation of the world established by the end of this trilogy, the events of which are referred to as the Fall. It is followed by the Kingdom of the Serpent
At first the books appear to be standalone novels, however ultimately they weave together to form one larger story, as sub-plots and themes coalesce in the final book, and only by reading that can you see how it all holds together. They do not need to be read in order of publication, although The Hounds of Avalon does bring together the characters from the other two and is set after the events of The Queen of Sinister and The Devil in Green.
This trilogy fits into a much bigger jigsaw, a sprawling story that covers two thousand years of history, multiple mythologies and two worlds, through The Age of Misrule and the Kingdom of the Serpent - again, the stories stand separately but a greater perception comes from reading all.
The Devil in Green has been described as "a sumptuous feast of fairytale, magic, dark gothic horror and romance."
All through his books Chadbourn buries archetypes, specifically those of Jung, to get across his ideas and tap into the subconscious. He has the Hero, The Great Mother The Wise old man The Trickster and the Child subtly underpinning his characters. But he makes sure his characters are real and flawed. His heroes are not stereotypical high born achievers but ordinary individuals from normal or hard backgrounds.