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Bela Lugosi as Dr. Melcher/ Monsieur Colomb |
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Clayton Moore as FBI Agent Richard ‘Dick’ Martin |
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Joan Barclay as Alice Saunders |
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George Pembroke as Dr. William Saunders |
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Robert Frazer as Amos Hanlin |
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Robert Fiske as Phillip Wallace |
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Irving Mitchell as John Van Dyke |
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Edward Peil Sr. as Ryder |
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Kenneth Harlan as FBI Chief Colton |
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Max Hoffman Jr. as Kearney |
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Joseph Eggenton as Stevens |
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I. Stanford Jolley as The Dragon |
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Frank Melton as FBI Agent |
| Production | Jack Dietz | Production Manager |
| Editing | Carl Pierson | Editor |
| Production | Sam Katzman | Producer |
| Directing | William Nigh | Director |
| Camera | Arthur Reed | Director of Photography |
| Sound | Johnny Lange | Music |
| Sound | Lew Porter | Music |
| Production | Jack Dietz | Producer |
| Art | Dave Milton | Art Direction |
| Sound | Glen Glenn | Sound Engineer |
| Sound | Heinz Roemheld | Music |
| Directing | Gerald Schnitzer | Assistant Director |
| Directing | Arthur Hammond | Assistant Director |
| Writing | Harvey Gates | Screenplay |
| Writing | Robert Kehoe | Story |
| Writing | Harvey Gates | Original Story |
