Sir James Blake has retired from Scotland Yard so that he can assist his niece Hope and her friend Jerry in developing an apparatus they have invented. Sir James thinks that their invention has the potential to prevent wars, and plans to donate it to the League of Nations. But a gang of criminals led by the elusive "Scorpion" steals the device, and Blake and his associates must recover the invention and determine the identity of the "Scorpion".
Ralph Byrd
as Jerry Sheehan
Joan Barclay
as Hope Mason
Lloyd Hughes
as Doctor Marshall
Dickie Jones
as Bobby Mason
Lucille Lund
as Duchess
Nick Stuart
as Julot
Sam Flint
as Chief Insp. Henderson
Gail Newbury
as Mimi - Policewoman
Jimmy Aubrey
as The Hag / Baron Polinka
Theodore Lorch
as Daggett - the Butler (as Ted Lorch)
George DeNormand
as Pedro - Henchman
Bob Terry
as Peyton - Henchman
