I thought this was pretty good. It takes place in Puerto Rico where a gang of diamond smugglers are at work. On the way over, Moto meets a professional wrestler who tags along with him (perhaps we could call them a tag team). Once they arrive, the military man in charge is under scrutiny for allowing things to occur under his watch. As is usually the case in these types of films, there are all kinds of suspects. Peter Lorre is at his best in this one as he must play roles in order to keep everyone off their game. A question I've been pondering has to do with how many white suits Moto has. Once again, as I've said at other times, "How is it that the bad guys can fire a hundred shots and not hit any of the good guys?" There are plot problems like over the place as well. But still it's pretty entertaining as are most of these films.

Herbert I. Leeds directs Peter Lorre in this episode of the Mr. Moto series. Diamond smugglers in Puerto Rico murder a lead investigator; this forces the U.S. Government to call upon super sleuth Kentaro Moto(Lorre)to further investigate and break up the suspected criminal ring. As always when summoned, Moto's powers of reason prove flawless when dealing with dim-bulb hoodlums. With martial arts and mental prowess, the unassuming and mild mannered Mr. Moto is victorious in meeting the challenge. Deadpan humor is not lost in the crime and drama. The supporting cast features: Jean Hersholt, Richard Lane, Amanda Duff, Leon Ames, Paul Harvey and Warren Hymer, as Twister McGurk.

Watched three Mr. Moto movies: One was "The Mysterious Mr. Moto". The 2ns one was, I think, "Mr. Moto's Last Warning".Maybe the best of the three was this one, "Mr. Moto in Danger Island: (1939) Danger Island is apparently Puerto RicoMr. Moto (Peter Lorre). Geez, I thought it would never end. But still, in this series, if you're a Lorre fan (I am)… I give it a "6". Not as high as others rated it.Mr. Moto picks up a sidekick, a wrestler named Twister Mcgirk, when he goes to Puerto Rico to investigate diamond smuggling and a missing investigator. (I didn't know diamond mines were big in Puerto Rico but that is explained). Twister's grammar makes Slip Mahoney (Bowery Boys) sound like Laurence Olivier.I saw Ward Bond among the wrestlers but he wasn't in the credits.I've been to Puerto Rico; I didn't see any swamps or quicksand but… okay. Maybe I missed it. All I saw was luxury hotels and beautiful beaches. Oh, and I didn't see any Puerto Ricans in this movie.

Not one of the brighter entries in the wildly uneven Peter Lorre-Sol Wurtzel Moto series, this one sets our hero on the trail of the obligatory jewel smugglers in glamorous, exotic PUERTO RICO, where he encounters a snippy library clerk and a tippy rowboat among other perils.