"The Mars Monopoly" by Jerry Sohl

A guy's gotta earn a living someplace—and if it isn't on Earth, it might as well be on Mars. That is if the Syndicate would let you live on the red planet. Bert Schaun found himself washed-up as a round-the-world rocket racer, blacklisted by Thornton McAllister. He tried to make a new life for himself prospecting for uranium in the lonesome vastness of the asteroids.

But McAllister's fury hunted him even to Mars; the issue became a struggle to stay alive against the dangers imposed by McAllister's interplanetary power. And then Bert met Emma, and found that he was not only fighting for his own survival and his sweetheart's, but for the survival, too, of a whole race of Martian outcasts.

Singlehandedly, he had to combat genocide on Mars

Jerry Sohl really wasn't all that prolific, but everything I've ever read by him has been outstanding. "The Mars Monopoly," which was originally part of an Ace Double, is pure science fiction adventure from start to finish. It's great. If you like Sohl, check out "The Haploids," "The Time Dissolver," "One Against Herculum," and his best novel, "Costigan's Needle. (Rebecca Lethlean, Amazon)