The Door Through Space by Marion Zimmer Bradley is now available at Gutenburg. Here is a short blurb of the book.
Wolf: a deadly world under a cold red sun, old when Terrans were learning to walk upright. Only one Terran agent knew Wolf well enough to pass undetected; but he had ruined his usefulness long ago. And yet only this scarred and bitter man could discover the secret of The Door Through Space...
