A planetary system with four habitable planets becomes the galaxy's maximum security prison because microorganisms found on the planets make it impossible for anyone to survive off planet after exposure. As a side-effect the microorganisms give their victims special powers such as telekinesis, shape-changing, or body swapping. Jack Chalker is an underrated Science Fiction writer. He had a gift for devising an odd premise and then carrying it through to its conclusion with a relentless internal logic.