Wikipedia
Nephté is an opera by the French composer Jean-Baptiste Lemoyne, first performed at the Académie Royale de Musique (the Paris Opéra) on 15 December 1789. It takes the form of a tragédie lyrique in three acts. The libretto, by François-Benoît Hoffman, is set in Ancient Egypt but is based on the story of Camma, Queen of Galatia taken from the ancient historian Plutarch.
The plot concerns Nephté, Queen of Egypt, whose husband King Séthos has been murdered by his brother Pharès. The widowed queen seeks revenge with the help of the high priest Amédès. However, Pharès has the support of the army and aims to take the throne and to marry Nephté himself. He also threatens the life of Nephté's son. Eventually, Nephté agrees to marry Pharès but she poisons the wedding cup, killing both the usurper and herself and allowing her son to succeed to the throne as king of Egypt.