The aliens that abducted our heroes, wanted the super-energy in Supermans body. Seems like a good plot, but as so many other books of the 80's, the story is too short. While I kind of liked the way the story folwed, it lacked a finality as Superman is freeded and they return to Earth. For example, what is to stop the two aliens from building another machine. Secondly do the brothers expire with no super-energy or still live forever, How does Superman know they will soon Die? Questions, Questions, Questions. As always any book with a Neal Admas cover is a winner in my eyes.