British diamond smugglers use the radiowoman (Phyllis Kirk) from a freighter docked on the Thames to unwittingly "mule" their swag, hidden in cigarettes, past customs, not knowing that she has befriended an Inspector for the Thames River Patrol.
John Bentley
Phyllis Kirk
Leonard White
Glyn Houston
Patrick Jordan
Harold Ayer
David Hurst
Charles Lloyd Pack
Robert Ayres
Ewan Roberts
Michael Balfour