In that future, Earth has been conquered by the Kyben, but all the surviving humans except Trent have mysteriously vanished. The aliens are being obliterated by a "radioactive plague" that is killing all intelligent life on the planet, apparently unleashed by the humans in a last-ditch effort to repel the invasion. In a desperate attempt to find a cure for the plague and to extract whatever knowledge is stored in the hand/computer, the Kyben have followed him back in time with the missing fingers.