In this episode captain Drummond tries to find the killer of various people. All assassinations were provoked by a diamond of great value, but Drummond will face the danger.
Action | Adventure | Crime | Mystery | Romance | Thriller
| John Barrymore | … | Col. Neilson | |
| John Howard | … | Capt. Hugh ‘Bulldog’ Drummond | |
| Louise Campbell | … | Phyllis Clavering | |
| Reginald Denny | … | Algy Longworth | |
| E.E. Clive | … | Tenny | |
| Porter Hall | … | Dr. Botulian | |
| Elizabeth Patterson | … | Aunt Blanche | |
| Nydia Westman | … | Gwen Longworth | |
| Michael Brooke | … | Anthony Greer | |
| Halliwell Hobbes | … | Prof. Bernard Goodman | |
| Matthew Boulton | … | Sir Raymond Blantyre | |
| Zeffie Tilbury | … | Mrs. Weevens | |
| David Clyde | … | Constable McThane | |
| Clyde Cook | … | Constable Sacker | |
| Austin Fairman | … | Roberts |