Jules Verne 
The Underground City; Or, The Black Indies [EPUB ebook] 

‘The Underground City; Or, The Black Indies’ is a novel written by Jules Verne, first published in French as ‘Les Indes noires’ in 1877. However, it should be noted that the English title of the novel is typically translated simply as ‘The Black Indies’ rather than ‘The Underground City.’
The story is set in the coal-mining region of Scotland and follows the adventures of a group of characters who become involved in a mysterious series of events surrounding the coal mines. As they investigate further, they uncover a hidden underground city built within the mines, inhabited by a group of people who have been living there in secret for generations.
‘The Black Indies’ explores themes of industrialization, technological innovation, and the clash between traditional ways of life and modernity. It is notable for its vivid descriptions of the underground world and its depictions of the challenges faced by the characters as they navigate the depths of the earth.
While not as well-known as some of Verne’s other works, such as ‘Twenty Thousand Leagues Under the Sea’ or ‘Journey to the Center of the Earth, ‘ ‘The Black Indies’ remains a notable contribution to the genre of science fiction and adventure literature.