A frightened woman is murdered in the London apartment of a well-known novelist named Henry Leroux. The police arrest Leroux's butler, but he escapes and runs off to a mysterious opium den, the lair of a drug dealer named Mister King. Gaston Max, a detective from Paris, arrives in London to investigate the drug trafficking. Although the police take down the gang, Mr. King escapes and manages to keep his true identity a secret.
| Directing | René Plaissetty | Director |
| Writing | Sax Rohmer | Writer |
| Writing | Gerard Fort Buckle | Writer |
| Production | Oswald Stoll | Producer |
| Crew | Jack E. Cox | Cinematography |