Otis Beagle and Joe Peel operated one of the most unethical private eye businesses in California. To put it briefly, they were unmitigated scoundrels. Blackmail was their special cup of tea--not nailing the blackmailers, but practicing it themselves. When one of their shakedowns failed, they had murder on their hands.
Used availability for Frank Gruber's Market for Murder
July 1992 : UK Paperback