Hugo Award winner Ben Bova and Les Johnson complete Bova’s Outer Planets series (Uranus, Neptune, and Pluto), a Grand Tour of the human settled solar system, with a final encounter on Pluto.

Major Larry Randall has been called to Pluto to retrieve Dr. Aaron Mikelson. Mikelson, no longer human after a horrific accident, is now melded to an AI. His enhanced senses have detected an alien artifact on Pluto’s surface, and he’s not leaving without it.

Transferred to the research vessel studying Pluto, Randall and the other scientists are stumped as to the artifact’s purpose and origin. Looking for similar signs of aliens they make their way to Pluto’s moon, Charon, where, buried deep under its icy surface, something stirs―and wakes.

Against a backdrop of unknown alien technology and potential interplanetary war, Mikelson’s inhuman ego and obsession will risk humanity by calling something unknown to our solar system.