The 10th century.
Fanatical Christians rebelling against the Pope dig deep into the Earth in a quest to find Hell.
The present day.
A group of American college students in England for the Royal Wedding descend into an abandoned medieval mine, where they encounter a hellish nightmare world. Getting in was easy. Getting out will unleash Hell on Earth.
keywords: subterranean fiction, dystopia, horror, underground world, dark fantasy, Christianity, cave exploration, journey to the center of the earth
Scott Reeves is the author of numerous science fiction and fantasy novels. He is also a poet and singer (not THAT Scott Reeves) whose poems can be heard as songs on YouTube, Spotify, Apple Music, Amazon, etc.