While serving a short sentence for theft, young and impressionable Malcolm Tanner formed a hero-worshipping friendship with his tough, ruthless cellmate Ernie Callan. After serving his sentence, Tanner is overjoyed when Callan offers to come and live with Tanner and his family while continuing his life of crime. However, joy turns to tragedy when it is learned that the police are hunting his mate, not only because of his criminal activities, but because he is a carrier of a deadly strain of smallpox.