G-Man Ted Riley is ordered to investigate happenings at Diamond Island, where a bogus Major Gray is reported engaged in manufacturing a new brand of secret gas for his own purposes. Riley blows up his motor boat just off the island and is picked up by Gray's men. On the island he discovers chemist Professor Baker (John Cowell) and his daughter, Anne, are held captive by Major Gray.
| Directing | Elmer Clifton | Director |
| Sound | Lee Zahler | Original Music Composer |
| Production | C.C. Burr | Producer |
| Art | Vin Taylor | Art Direction |
| Sound | Corson Jowett | Sound |
| Directing | George Jeske | Assistant Director |
| Editing | Tony Martinelli | Editor |
| Production | James Altwies | Production Manager |
| Writing | Homer King Gordon | Screenplay |
| Camera | Irving Akers | Director of Photography |
| Crew | George Jeske | Additional Dialogue |
