H G Wells 
The Time Machine (World Classics, Unabridged) 

When a Victorian scientist propels himself into the year a.d. 802, 701, he is initially delighted to find that suffering has been replaced by beauty, contentment, and peace. Entranced at first by the Eloi, an elfin species descended from man, he soon realizes that these beautiful people are simply remnants of a once-great culture—now weak and childishly afraid of the dark. They have every reason to be afraid: in deep tunnels beneath their paradise lurks another race descended from humanity—the sinister Morlocks. And when the scientist’s time machine vanishes, it becomes clear he must search these tunnels if he is ever to return to his own era.