Wendy (Gloria Jean), a naive young girl, lives with her kindly Uncle Bill (John Qualen), who has sheltered her from life by instilling a belief in fairy-tales and make-believe. Uncle Bill, a pawn shop owner buy a violin from shady character, Peg-Leg ('Sheldon Leonard' )qv)). When Johnny (Keefe Brasselle, a neighborhood boy and friend of Wendy, connects the violin with the theft of a Stradivarius from a murdered composer, he is kidnapped by a group of thugs. Peg-Leg is killed by the boss of the crime-ring, a face-disguised mystery man known as Raincoat. He tortures Johnny to make him reveal his knowledge of the gang's activities. Meanwhile, Gloria his discovered the identity of 'Raincoat' and seeks the help of Mike ('Bill Goodwin'), the policeman on the beat.