The great Victor Hugo once said that Paris's underground sewers were the city's conscience. Because compared to the filthy upper class on the ground, homeless people, beggars, thieves, gypsies and all kinds of poor people gather in the sewers. Although they live in dark corners, they often have purer emotions and sincere mutual support. Compared with the hypocrisy, cover-up, and infighting in the earthly world, Hugo believed that the people in these sewers were a group closer to the essence of morality. So Hugo eulogized and praised this sewer. In his opinion, what was ugly was not the environment of the sewer, but the corruption and hypocrisy hidden in the name of a bright appearance on the ground.
However, more than a hundred years later, Hugo may not have expected that the underground world is no longer a damp and dirty secret passage, but has transformed into a huge underground city...
