McGarrett's sister, whose infant son is dying of cancer, has fallen under the sway of a medical quack. Her husband is afraid to confront her. Instead, he summons McGarrett to their home in Los Angeles. McGarrett enlists the aid of U.S. Food and Drug Administration officials in prosecuting the quack. However, McGarrett's sister refuses to believe her big brother. When the child dies, the sister turns against McGarrett. As the trial begins, it is disrupted by followers of the quack.