Explained in example sentence
"Oblivion" is right; further misadventures of Reggie and Mike pursuing the Tall Man still leave too much unexplained; we do find out the Tall Man's identity (Jebediah Morningside) and how he became interested in his "work", but it's never explained exactly how he got his supernatural powers, what exactly the "other side" is, what the flying spheres are or where they came from, how the "other side" transforms bodies into gnomes, and most of all, we still don't know what in the HELL the Tall Man means to do with his evil power.