The nobles are seized and condemned to death, but on _Adriano's_ pleading they are spared. They, however, violate their oath of submission, and the people again under _Rienzi's_ leadership rise and exterminate them, _Adriano_ having pleaded in vain. In the end the people prove fickle. The popular tide turns against _Rienzi_, especially in consequence of the report that he is in league with the German emperor, and intends to restore the Roman pontiff to power. As a festive procession is escorting him to church, _Adriano_ rushes upon him with a drawn dagger, being infuriated at the slaughter of his family, but the blow is averted. Instead of the "Te Deum," however, with which _Rienzi_ expected to be greeted on his entrance to the church, he hears the malediction and sees the ecclesiastical dignitaries placing the ban of excommunication against him upon the doors. _Adriano_ hurries to _Irene_ to warn her of her brother's danger, and urges her to seek safety with him in flight. She, however, repels him, and seeks her brother, determined to die with him, if need be. She finds him at prayer in the capitol, but rejects his counsel to save herself with _Adriano_. _Rienzi_ appeals to the infuriated populace which has gathered around the capitol, but they do not heed him. They fire the capitol with their torches, and hurl stones at _Rienzi_ and _Irene_. As _Adriano_ sees his beloved one and her brother doomed to death in the flames, he throws away his sword, rushes into the capitol, and perishes with them.
The overture of "Rienzi" gives a vivid idea of the action of the opera. Soon after the beginning there is heard the broad and stately melody of _Rienzi's_ prayer, and then the Rienzi Motive, a typical phrase, which is used with great effect later in the opera. It is followed in the overture by the lively melody heard in the concluding portion of the finale of the second act. These are the three most conspicuous portions of the overture, in which there are, however, numerous tumultuous passages reflecting the dramatic excitement which pervades many scenes.
The opening of the first act is full of animation, the orchestra depicting the tumult which prevails during the struggle between the nobles. _Rienzi's_ brief recitative is a masterpiece of declamatory music, and his call to arms is spirited. It is followed by a trio between _Irene_, _Rienzi_, and _Adriano_, and this in turn by a duet for the two last-named which is full of fire. The finale opens with a double chorus for the populace and the monks in the Lateran, accompanied by the organ. Then there is a broad and energetic appeal to the people from _Rienzi_, and amid the shouts of the populace and the ringing tones of the trumpets the act closes.