McGarrett sends an undercover agent into a rehabilitation home for juvenile offenders to find out who is behind the theft of gold from dental supply warehouses.
Ben Tanaka, a well-known ecologist, seems to be behind the kidnapping of a wealthy land developer's wife, but all is not as it seems and a conspiracy gradually reveals itself.
Whilst trying to stop the smuggling of small Oriental animal statues, McGarrett is caught illegally in possession of one of them as part of his personal collection.
Danno's Aunt Clara becomes acquainted with a man on the plane to Honolulu, but becomes concerned about him afterwards. Dan, Steve and the others ignore her at first, but then the man turns up dead...
When a letter bomb kills a Naval Officer whilst McGarrett is on Navy Duty, he is called upon to investigate and uncovers a plot involving an old nemesis...