The struggle is a short one.  The nobles are overcome, and in the second act they appear at the Capitol to acknowledge their submission to Rienzi:  but Adriano, who has been among them, warns Rienzi that they have plotted to kill him.  Festal dances, processions, and gladiatorial combats follow, in the midst of which Orsini rushes at Rienzi and strikes at him with his dagger.  Rienzi is saved by a steel breastplate under his robes.  The nobles are at once seized and condemned to death.  Adriano pleads with Rienzi to spare his father, and moved by his eloquence he renews the offer of pardon if they will swear submission.  They take the oath only to violate it.  The people rise and demand their extermination.  Rienzi once more draws the sword, and Adriano in vain appeals to him to avert the slaughter.  He is again successful, and on his return announces to Adriano that the Colonnas and Orsinis are no more.  The latter warns him of coming revenge, and the act closes with the coronation of Rienzi.

The fourth act opens at night near the church.  The popular tide has now turned against Rienzi, upon the report that he is in league with the German Emperor to restore the pontiff.  A festive cortege approaches, escorting him to the church.  The nobles bar his way, but disperse at his command; whereupon Adriano rushes at him with drawn dagger, but the blow is averted as he hears the chant of malediction in the church, and sees its dignitaries placing the ban of excommunication against Rienzi upon its doors.  He hurries to Irene, warns her that her brother’s life is no longer safe, and urges her to fly with him.  She repulses him, and seeks her brother, to share his dangers or die with him.  She finds him at prayer in the Capitol.  He counsels her to accept the offer of Adriano and save herself, but she repeats her determination to die with him.  The sounds of the approaching crowd are heard outside.  Rienzi makes a last appeal to them from the balcony, but the infuriated people will not listen.  They set fire to the Capitol with their torches, and stone Rienzi and Irene through the windows.  As the flames spread from room to room and Adriano beholds them enveloping the devoted pair, he throws away his sword, rushes into the burning building, and perishes with them.

The overture of “Rienzi” is in the accepted form, for the opera was written before Wagner had made his new departure in music, and takes its principal themes, notably Rienzi’s prayer for the people and the finale to the first act, from the body of the work.  The general style of the whole work is vigorous and tumultuous.  The first act opens with a hurly-burly of tumult between the contending factions and the people.  The first scene contains a vigorous aria for the hero ("Wohl an so moeg es sein"), which leads up to a fiery terzetto ("Adriano du?  Wie ein Colonna!”) between Rienzi, Irene, and Adriano, followed by an intensely passionate scene ("Er geht und laesst dich meinem Schutz”)