When the shadows come to life

Hundreds of years have passed since the hordes of Lucifer destroyed the world. Hundreds of years, the remnants of mankind, the ancient peoples of Tuata de Danann and Firu Bolg, live in underwater cities, hiding from hungry darkness. Without sunlight, without wind, without the noise of foliage. They love and hate, are born and die, gradually forgetting who they are, where they came from. History corresponds, and faith changes, subordinating the minds, creating a new reality.
But sometimes the past suddenly imperiously reminds of itself. Awakened evil, ancient books, an echo of past achievements. Scary fairy tales become real, and complex decisions are falling on those who do not want to make them