Sir James Blake has retired from Scotland Yard so that he can assist his niece Hope and her friend Jerry in developing an apparatus they have invented. Sir James thinks that their invention has the potential to prevent wars, and plans to donate it to the League of Nations. But a gang of criminals led by the elusive “Scorpion” steals the device, and Blake and his associates must recover the invention and determine the identity of the “Scorpion”.
Crime | Sci-Fi
| Ralph Byrd | … | Jerry Sheehan (archive footage) | |
| Herbert Rawlinson | … | Sir James Blake (archive footage) | |
| Joan Barclay | … | Hope Mason (archive footage) | |
| Lloyd Hughes | … | Dr. Marshall (archive footage) | |
| Dickie Jones | … | Bobby Mason (archive footage) | |
| Lucille Lund | … | The Duchess, a Gang Moll (archive footage) | |
| Nick Stuart | … | Julot, Male Apache Dancer (archive footage) | |
| Sam Flint | … | Chief Inspector Henderson (archive footage) | |
| Gail Newbury | … | Mimi, policewoman posing as dancer (archive footage) | |
| Jimmy Aubrey | … | Baron Polinka (archive footage) | |
| Theodore Lorch | … | Daggett, the butler (archive footage) | |
| George DeNormand | … | Gang Member posing as Newshawker (archive footage) | |
| Bob Terry | … | Peyton, lead thug (archive footage) | |
| William Farrel | … | Count Basil Zagaloff (archive footage) | |
| Frank Wayne | … | Charles (archive footage) |