Arvire et Évélina
On the isle of Mona, Roman general Messala tries to capture British king Arvire with help from his sons Irvin and Vellinus. Irvin reveals the plot and leads the British defense, while Vellinus first betrays Arvire and later repents. The Britons defeat the Romans and free Évélina from captivity; Arvire releases Messala and his men and promises Évélina to Irvin in marriage.