The Voices of Heaven — Frederik Pohl

Barry di Hoa had the good life on the Moon: steady work and the love of a good woman. But a rival slipped him a mickey, and he next awoke aboard Gerald Tscharka's ship as it neared the colony planet, Pava, eighteen light-years away.

Pava was the frontier, complete with earthquakes, primitive conditions and hard physical work. The local "doctor" wouldn't treat Barry's little manic-depressive problem without medicine from the Moon. And the Millernarist colonists, who thought suicide was cool fun, didn't thrill him.

Then he made friends with the leps. The large, caterpillar-like, odd-speaking gentle beasts were helping the humans to fashion a life on their planet. In their strange way, they knew things about Pava that might make the difference in the colony's survival. He started to believe he could really enjoy life in this fragile paradise. Except Tscharka was up to soemthing bad, something that would change eveyrthing. Barry knew only he could stop the mad captian, and the captain knew it, too. What neither knew was whether Barry could be manic enough to do it.