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