Boat building father and son join the river patrol service and get caught-up in a spy ring.
Tom Gamble
as Nobby Clark
Edward Rigby
as Joe Clark
Jean Gillie
as Nancy
Michael Wilding
as Dick
Marion Gerth
as Mimi
Mavis Villiers
as Blondi
John Salew
as Henri
Henry B. Longhurst
as Admiral Drake
G.H. Mulcaster
as Admiral Reynolds
Dennis Wyndham
as Captain Raleigh
Ian McLean
as First C.I.D. Man
Joan Hickson
as Woman Carried Ashore
