A sinister crook is implicated in blackmail, greed for emeralds, a secret formula and murder. Thee episodes from a 1952 British television series called "Inspector Morley, Late of Scotland Yard, Investigates" were joined together and released theatrically.
Unfortunately the movie King of the Underworld is not yet available on HBO Max.
| Sound | W.L. Trytel | Music |
| Production | Gilbert Church | Producer |
| Directing | Victor M. Gover | Director |
| Art | Don Chaffey | Art Direction |
| Editing | Helen Wiggins | Editor |
| Writing | John Gilling | Writer |
| Costume & Make-Up | Harry Webber | Makeup Artist |
| Sound | Peter Birch | Sound Recordist |
| Camera | S.D. Onions | Director of Photography |
| Directing | Gladys Reeve | Continuity |
| Directing | John Workman | Assistant Director |
