In Puerto Rico to investigate a glut of contraband diamonds that are flooding the world's jewel market, Mr. Moto and his sidekick, a wrestler, find themselves involved in murders by thrown daggers, the frame-up of an overstressed Army colonel, and a pirate gang led by an unknown boss who has inside knowledge of the ensuing investigation.
Peter Lorre
Warren Hymer
Amanda Duff
Robert Lowery
Leon Ames
Jean Hersholt
Douglass Dumbrille
Richard Lane
Charles D. Brown
Paul Harvey
Eddie Marr
Harry Woods
Ward Bond
Neely Edwards
Renie Riano
Willie Best
Grace Hayle
Edwin Stanley
Walter Deming
Lester Dorr
Donald Douglas
Jimmie Dundee
Ralph Dunn
Juan Duval
Harold Goodwin
Oscar 'Dutch' Hendrian
Selmer Jackson
Edward Keane
Al Kikume
George Magrill
Tony Martelli
Louis Mercier
Lucille Miller
Gloria Roy
Lee Shumway
Jack Stoney
Harry Strang
Max Wagner
Ray Walker