Second from the Sun, by E.C. Tubb (epub/Kindle)
Venus was a horror-world, a place of teeming, nightmare danger, yet with the danger went wealth, and in the Hotlands rested a secret. To find the secret was one thing: to get out alive was another matter.
E.C. Tubb wrote the long-running Dumarest space opera series, as well as many other fine science fiction novels during his long career.