McGarrett investigates the mysterious murder of Anna Schroeder, who had just recently collected insurance money following her husband's death in Vietnam. Before long, he realizes this is the latest in a series of similar murders - an apparent scheme to collect the insurance payoffs for servicemen killed in action, and involving fraudulent marriage licenses. Two of those involved never expected murder, and when one of them tries to bow out, the ringleader drives him to a deserted curve of road and pitches his heart pills over a cliff before leaving him there to die. A young woman named Yoko agrees to help McGarrett trap the suspect, but McGarrett doesn't realize what's really going on, and that almost costs Yoko her life!