Charlie Chan, with son Jimmy on a week's pass from the Army, takes up a request for help at a castle-home, miles from anywhere in the American desert south-west and inhabited by an eccentric, reclusive historian and his wife, a descendant of Lucrezia Borgia. Once there, he finds the request's legitimacy denied by all who are present, but still necessary as one houseguest has already been murdered, the other guests are at each other's throat, and the Borgia-related chatelain is suspected...
| Directing | Harry Lachman | Director |
| Writing | John Francis Larkin | Screenplay |
| Writing | Earl Derr Biggers | Characters |
| Editing | John Brady | Editor |
| Art | Lewis H. Creber | Art Direction |
| Art | Richard Day | Art Direction |
| Production | Ralph Dietrich | Producer |
| Camera | Virgil Miller | Director of Photography |
| Art | Thomas Little | Set Decoration |
| Costume & Make-Up | Herschel McCoy | Costume Design |
| Production | William Koenig | Production Manager |
| Sound | Bernard Freericks | Sound |
| Sound | Harry M. Leonard | Sound |
