The Lucky Stiff (1949)

Semi-successful lawyer John Malone is intrigued by local night club singer Anna Marie St. Clair. After meeting her at the club, he is present when her boss (and more?) is killed, and she is arrested for the crime. Sentenced to death, Malone and his faithful secretary set out to find the real murderer, who is probably also responsible for a protection racket Malone is investigating.