If you know Richard Prather at all it is from his Shell Scott novels and stories written in the fifties and sixties. They're about a hepper-than-hep Hollywood private eye who you have the feeling the Rat Pack would have hired when they needed some help. Though mostly forgotten today they were enormously successful -- only Mickey Spillane and God outsold Prather in the fifties -- and still a lot of fun.
The Peddler is a Hard Case Crime Club re-release of an earlier non-Shell Scott Prather book from 1952. It's the story of a man's rise in the San Francisco prostitution racket. The tone is dark and the book is very dialog heavy. Like much of Hard Case, it's good but not great and enjoyable but a little unsatisfying. There is a great scene in the middle when a raid on a rival brothel goes bad and an ending curiously reminiscent of Out but I doubt it inspired Natsuo Kirino.