anger has a special sparkle when Mr. Moto heads to Puerto Rico to put a stop to the glut of contraband diamonds that are flooding the world's jewel market! But his smuggling investigation quickly turns into a murder mystery when both an undercover government agent and a top political figure wind up dead—and Moto begins to suspect that he is going to need a gem of a plan... to put these crooks on ice!

Overview from themoviedb.org