This is a space opera & yet Morressy adds in a fable element & turns it into a morality tale. It's kind of a hokey world in some ways. A galactic civilization that has reverted to barbarism. They fly spaceships, but can't build them any more. They were all built by the vanished humans of Earth who are mostly cursed for lording it over them for so long. There are many races & they can usually interbreed, but Earth men found them. They also found remnants of another star spanning race, but no one really knows if there was only one or not.
There is a lost treasure, pirates, slavers, & even barbaric planetary tribes/races. Guns are mostly a lost art, but there are plenty of swords & some nifty, high tech gadgets. Into this mess comes Jorry, a schemer, who is after a long lost treasure. To this end he's recruited various companions. We follow them through various trials to a great conclusion.
It's been a long time since I last read this, at least a couple of decades. I should read more of his books. I mostly remember his fantasy books, but he's done great with SF.