Austin 360 When you think of "Tosca," one of the world's most beloved operas, you might conjure up lofty melodies, virtuoso performances and dramatic action that includes murder, suicide and a good deal of associated suffering. You might envision, too, elaborate scenery and costumes depicting 1800s Rome, as Napoleon's troops enter a city ruled by Scarpia, the sadistic chief of police who tortures the painter Cavaradossi in order to force the artist's beloved, opera singer Tosca, into his bed. Did I say it was a melodrama? It is. But a surprisingly effective one. Puccini's almost Wagnerian score ranks alongside his other operatic zeniths, such as "La Boheme," "Turandot" and "Madama Butterfly."