 Descius Heiss (Oscar Homolka) is a French expatriate, and former Devil s Island prisoner, with two passions; driving shrewd bargains in antiques at his Sly Corner Shop, and the care of his motherless, violin-playing daughter, Margaret (Muriel Pavlow.)But, his comfortable wealth comes more fom being a fence for stolen goods than it does buying-and-selling antiques. His secret is discovered by his shop assistant Archie Fellowes (Kenneth Griffith), a nasty, sniveling young rat, and he begins blackmailing Heiss. Heiss employs the usual solution to blackmailers, and the film ends in a London concert-hall where Margaret is playing the Mendelssohm Violin Concerto.