Charon: A Dragon at the Gate (The Four Lords of the Diamond, Vol. 3)

Somewhere, from among the four human settled worlds of the Warden Diamond, hostile aliens were spying on Earth. But no agent could be sent to investigate and report back. All trips to the Warden worlds were one-way. There a microscopic symbiont called the warden bug invaded all life forms, after which life became impossible outside the Warden system. Sitting on a freighter in the "safe" zone of the solar system, the Confederacy's best agent receives reports tightbeamed from former criminals imprinted with his mind. This is the third report from the agent imprinted for Charon. A hot hellish world, Charon was a place where magic works and strange beast lurk. Park Lacoch, a small almost elfin man was known on the outside as the "Butcher of Bonhomme". Using Park's administrative background he planned on infiltrating a group of rebels already intent on deposing the current Lord. They took the body of Park Lacoch and stripped away his mind. Then they stuck him aboard a spaceship and exiled him to Charon, from which no return was possible. And just when he thought things couldn't get any worse, Park found himself transformed into a changeling -- a half-beast, half-man, with the beast rapidly gaining ascendancy . . .