E.C. Tubb 
Nectar of Heaven 
The Dumarest Saga Book 24

The planet had two unique elements. One was that it produced the galaxy’s most desirable hallucinatory drug. The other was that it was a stock broker’s paradise.The world was split into rich men’s holdings — and every hour, every minute these were being traded on a continuous stock-market. Up and down went values as men conspired to seize others’ properties, to push prices down and costs up. Their money game controlled everything else — the common people, workers, farmers, homes, lives, poverty and luxury . . . Earl Dumarest went there to find his next stake. Find the drug-gem or manipulate the market — two possibilities. But behind the scenes stood the advisors of the inhuman Cyclan, determined to fix the odds against Dumarest . . . (First published 1981)