Never Love a Stranger (1958)

Frankie Kane is brought up in a Catholic orphanage and befriends Martin Cabell, a Jewish law student whose sister Julie becomes Frankie's sweetheart. At sixteen, Frankie learns that he is himself Jewish and therefore has to be moved to a Jewish home. That prospect proves so awful that he runs away - and goes bad. Years later, he returns to the district and gets involved with a crime syndicate that his old pal Martin, now assistant district attorney, has pledged to clean up. Frankie however, bumps in to Julie again and, finding he still loves her, decides to help the straight-shooting Martin smash the syndicate.