Hector, the dog of an officer of the merchant navy, wanders during a stopover in Lisbon. Captured by smugglers, he is soon used as a mule in a case of diamond smuggling. But this is not counting on his innate sense of justice and law...

Guy Stockwell
as Max

Craig Hill
as Bill

Walter Gotell
as Benton

Edmund Hashim
as Duke

Ed McCready
as Adolph

Eric Pohlmann
as Hugo

Fortunio Bonanova
as Inspector

Henry Brandon
as Circus Roustabout

Paul Devlin
as Crew Member

John Stacy
as Captain