A notorious Chicago lawyer leaves his successful practice and goes to Hawaii to locate his missing son who abandoned a promising law career and has become involved in drug smuggling.

A failed Quinn Martin pilot for a series starring a Hawaii-based government counter intelligence agency run by the indomitable Aunt Mary. In this, his only adventure, Diamond Head has to prevent the evil Tree from stealing a deadly nerve toxin gas and selling it to foreign powers. To help Diamond Head is the Dragon Lady and Zulu.

In this pilot film to the "Hawaii Five-0" television series, special law officer Steve McGarrett tracks down Red Chinese operatives and their spy ring in Honolulu.