Racine, Wisconsin, 1950s. As the streets of the Mid Western harbor city of Racine is recovering from one crime syndicate, another rears its ugly head. The mysterious Black Diamond is flooding the streets with cocaine and the police are at a loss to stop it. Then several thugs are found cut up in a parkign garage. Detective Garfield Teague sets out to investigate this strange new development. Who or what is The Black Diamond seemingly always two steps ahead of him and is the strange vigilante wearing a hideous mask an ally or another enemy?