From publisher blurb:
Introducing the Hollow Earth chronicle for Mage: The Ascension 20th Anniversary Edition, this is the first story that will hint to characters about a previously lost world.
Lands and Legends Lost in Time
Mythology and fantasy are systematically pushed further and further into the reaches of dreams and subconscious. They thrive in their new homes and wait to be rediscovered by true believers. Other legends, however, are deemed too strange or too fantastic to be given any credibility at all. Those stories fall into the depths of the Earth, presumably to be discredited and ridiculed forever.
Atlantis. Eldorado. Shang-ri La.
The Lost Legends Accept Their Fate
Exiled from the world and dreamers, the banished persevered in their new home and found their own purpose. Humanity continued to unknowingly help. Denial and banality separated, bound, and protected the rejected legends. The Rejected thrived without the outside interference. Some have developed into new incarnations, and others retain their ancient glory.
Yet, none harbor any love for the surface empires, and they resent their intrusions.
The Hallean Effect presents a cabal of mages who discover the dangers of blindly wandering into a part of the world that no longer wants to be found.