The Bridge of Sighs (1936)

Assistant District Attorney Jeffery Powell has just sent an innocent man to prison for the murder of a gambler. Powell is in love with, Marion Courtney, but he's unaware that Marion is the sister of the innocent man he sent to prison. Marion gets herself committed to a women's prison to get proof from inmate, Evelyn 'Duchess' Thane, that her brother is innocent. Powell learns of Marion's plight and believes she's in love with the man he sent to prison.