Even the opening credits as a police car races at high speed down a city street is exciting!The plot in summary is that "The Ghost" seeks revenge against the people that he feels are responsible for his brothers death.With the aid of a mechanical device,he can make himself invisable.The special effects for this are excellent.Ralph Byrd reprises his role as Tracy,and Ralph Morgan is his adversary.Music,photography,acting and direction are first rate.Another excellent Tracy serial from Republic.