Author/explorer John W. Vandercook conceived the character of Bertram Lynch as an investigator for the League of Nations. He is Trinidad's Port o' Spain trying to track down the leader of a gang of diamond smugglers. A trail, littered with murders, leads him to a crocodile-infested swamp.
| Actor | Role |
|---|---|
 Nigel BruceBertram Lynch | Bertram Lynch |
 Heather AngelJoan Cassell | Joan Cassell |
 Victor JoryHoward Sutter | Howard Sutter |
 Murray KinnellColonel Bruce Cassell | Colonel Bruce Cassell |
 Douglas WaltonGregory Bronson | Gregory Bronson |
 J. Carrol NaishDuval | Duval |
 Claude KingThe Governor Sir Ellery Bronson | The Governor Sir Ellery Bronson |
 Pat SomersetInspector R. Gordon Henley | Inspector R. Gordon Henley |
 Francis FordDavenant | Davenant |
 John DavidsonGookol Moah | Gookol Moah |
 Noble JohnsonQueechie | Queechie |
 Everett BrownNative | Native |