The first operas by Mozart, Wagner, Verdi, and Puccini came and went, never to enter the standard repertory. Dead Man Walking, the first by Jake Heggie, was an instant classic. Set to a libretto by Terrence McNally, the work had its premiere in San Francisco in 2000, starring Susan Graham as Sister Helen Prejean, the nun who befriends and administers to a hardscrabble murderer on Death Row. In the Chicago premiere, Graham returns to the opera for the first time as Mrs. DeRocher, the killer’s soft-spoken mother. Patricia Racette and Ryan McKinny, both in role debuts, play Sister Helen and Joseph DeRocher. —M.G.