Berenice, regina d'Egitto, HWV.38

The scene is Egypt, around 80 BC. The Queen, Berenice, has for some time been in love with a prince of Macedonia, Demetrio, but has been advised that for the good of her country she must form an alliance with Rome through marriage, and she has reluctantly consented to set aside personal feeling for duty. Demetrio is an ally of the enemy of Egypt, Mithridates of Pontus. Fabio, the Roman ambassador, presents the Queen with the man chosen by them to be her husband, Prince Alessandro of Rome. Alessandro falls madly in love with Berenice at first sight, but she is not as impressed with him and resents having a husband forced on her in this way. Fabio tells Alessandro that if Berenice refuses to marry him, he must wed her sister Princess Selene, instead.
Unbeknownst to the Queen, however, the man she loves, Demetrio, and her sister Selene are secretly in love with each other. Moreover, they are plotting to call Mithridates to their aid to overthrow Berenice and put Selene on the throne in her place. Berenice tells her sister that she must marry Prince Arsace (who in fact is in love with Selene, but not she with him). Alessandro saves Demetrio from an assassination attempt in the royal palace, whereupon Berenice resolves more than ever that Demetrio is the man for her.

Rome continues to press for Alessandro to marry Selene now that Berenice has refused him, but the Queen insists this is impossible, since Selene is now betrothed to Arsace. Berenice is warned this will mean war with Rome. Selene explains to Demetrio that she has no desire to wed Arsace but has no choice in the matter. Demetrio wants to kill Arsace in revenge. Arsace offers to yield Selene to Alessandro to avert war, but Alessandro has no interest in marrying anyone but his beloved Berenice. The Queen overhears the man she loves, Demetrio, ranting and raving to his sweetheart, her sister Selene, about how he never cared a bit for the Queen and in fact is plotting her overthrow, and Berenice orders Demetrio thrown into the dungeon.

Queen Berenice, utterly distraught with the knowledge that the man of her heart, Demetrio, never cared anything for her and is a traitor to boot, declares to the Roman envoy Fabio that she no longer cares whom she marries. She takes a ring off her finger and gives it to him, telling Fabio to give the ring to his choice, and whoever returns it to her will be the man she will wed. Fabio bestows the ring on Alessandro. Selene is desperate for Demetrio to be released from the dungeon and promises to Arsace she will marry him if only he can release Demetrio. Alessandro agrees to Arsace's request to help in the release of Demetrio, and Arsace determines to try to convince the Queen of Alessandro's sincere love for her. Berenice, however, is still furious and in emotional turmoil. She orders Demetrio to be decapitated and his severed head presented to her after which she plans to commit suicide. Selene pleads with her sister for mercy for Demetrio, a petition Alessandro and Arsace also urge to the Queen. Alessandro admits that he was given Berenice's ring by Fabio, but does not want to use it to claim the Queen's hand as he wants her to love him for himself. On hearing this, Berenice is touched and decides that she really does love Alessandro after all. She orders Demetrio released from the dungeon and forgives him, allowing him to marry Selene, while she will wed Alessandro.