Two private detectives find themselves up against an unsolved mystery or at least unseen mystery. Tommy Nelson, a boxer goes to them for help into proving that he was set up for the murder of his...

Two private detectives find themselves up against an unsolved mystery or at least unseen mystery. Tommy Nelson, a boxer goes to them for help into proving that he was set up for the murder of his fight manager. Tommy takes Claude Rains' charcter's serum to make him invisible. When the two private detectives realize what has happened to Tommy they agree to help him clear his name.