THE Argument, taken partly from Briani's libretto, relates some political history, how Isacio (Isaac Comnenus) obtained the throne of Cyprus from the Byzantine Emperor by forgery, followed by a military victory over his successor, which ‘puffed him up with Pride, and made him insolent and cruel … Hence he refused the port of Limissus [Limassol] … to the English Navy, without having any regard for the Princess of Navarre [Berengaria in history, Costanza in the opera], who was there to espouse Richard [Coeur de Lion], and who had laboured her Way thither through a strong and violent Tempest’. The date is ‘towards the Year’ 1190 [recte 1191]. Richard was on his way to the Third Crusade. ‘The Scene is the Court of Limissus, and the Palace of Isacius’.

Act I. Like a certain later opera set on the coast of Cyprus, Riccardo Primo begins with a spectacular storm. The Coast near Limissus, a tempestuous Sea, with Ships bulging [rotta] amongst the Rocks. Costanza, with her ‘Cousin and Tutor’ Berardo is in despair over the fate of Riccardo; although she has never seen him, she claims to adore him and wants to die if he has perished. Isacio, his daughter Pulcheria and Oronte, ‘Prince of Syria, Confederate’ of Isacio, arrive with Guards. In reply to Pulcheria Costanza says her name is Doride, and her companion is her cousin Narsete; Costanza perished in the storm. Isacio, impressed by her manner (‘Quanto e gentile!’), tells Pulcheria to entertain the strangers in his palace and prepare for her wedding to Oronte. She is happy to obey both commands. She takes Costanza by the hand and they go out followed by Berardo, but Oronte is held back by Isacio. Isacio orders Oronte to burn the wrecked British ships and leaves. Oronte gives vent to his passion for Pulcheria. In A Pavilion not far from the Rivers of Limissus Riccardo, with his Commanders and a letter open in his hand, from which he has learned that Costanza is at Isacio's court, resolves to go there, where he is not known. He likewise burns with passion for a woman he has never seen.