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.

性感发廊女克莱尔的后院藏着自己的犯罪男朋友杜克。杜克在一次作案后连累自己的兄弟被枪击中，惊慌失措的他找到靠山史蒂夫，开着偷来的车打算逃走。警方抓到史蒂夫后认为史蒂夫就是杜克进而要把他关进监狱，此时杜克不顾以往兄弟情深死活不站出来认罪，然而事情发生了转变...