...(note the reference to HG Wells' earlier time travel tale!)
Victorian inventor John travels to the future, where he discovers humans reached a remarkable level of scientific achievement, then apparently lost their knowledge over generations and became gentle primitives!
But not all of them!
When his time-travel vehicle is stolen and taken underground, John pursues the thieves, he discovers some humans had become savage primitives!
Adapted by Peter Stone, with layouts by Neal Adams and finishes by Adams, Rodolfo Damaggio, Andres Klasic, and John Nyberg, this adaptation takes considerable liberties with the original novel.