Dick Tracy's foe for this serial is the crime boss and Masked Mystery Villain The Spider/The Lame One and his Spider Ring. In the process of various crimes, including using his Flying wing and sound weapon to destroy the Bay Bridge in San Francisco and stealing an experimental "Speed Plane", the Spider captures Dick Tracy's brother, Gordon. The Spider's minion, Dr. Moloch, performs a brain operation on Gordon Tracy to turn him evil, making him secretly part of the Spider Ring and so turning brother against brother.
Ralph Byrd
as Dick Tracy
Kay Hughes
as Gwen Andrews
Smiley Burnette
as Mike McGurk
Lee Van Atta
as Junior
John Picorri
as Moloch
Carleton Young
as Gordon Tracy, after
Fred Hamilton
as Steve Lockwood
Francis X. Bushman
as Chief Clive Anderson
John Dilson
as Ellery Brewster [Chs. 1, 12]
Richard Beach
as Gordon Tracy, before [Chs. 1, 12]
Byron Foulger
as Korvitch [Chs. 1, 12]
Roscoe Gerald
as Power Co. Watchman-Thug (uncredited)
