This is the 4th and final Tracy serial and this one carries a lot of science fiction elements with it.
In this one Tracy battle "The Ghost" a mysterious criminal who is capable of making himself invisible and plans to wipe out New York and every member of the city's crime commission.
There are some great action scenes in this and in particular two very violent fights between Tracy and The Ghost. The ending is the most violent of all the Tracy serials, and one you won't forget.
Ralph Byrd is Tracy, of course and the rest of the cast includes Michael Owen, Jan Wiley, Ralph Morgan, John Davidson and Kenneth Harlan.
If you like the old republic serials, I recommend you check this one out.