During a stop off on a bird-watching expedition, tourists photograph an old sugar mill. They don't know that the mill is a front for a gold-smuggling operation and that one of their photographs has caught the leader through a window. The leader sends a pack of goons to kill everyone in the tourist party and steal their film. McGarrett and a newspaper journalist, who got hold of the pictures, must try to identify the man in the picture and take down his operation before he gets them.

The series concludes with the final showdown between McGarrett and Wo Fat. Three scientists who have disappeared have one thing in common, they all attended a symposium on possible space-based, laser defense systems. McGarrett impersonates a fourth scientist, Dr. Elton Raintree, who attended the same gathering and is soon abducted. Wo Fat is behind it all and wants the scientists to complete their work and produce such a device.