Theseus returns in disguise to fight for his father, the Athenian king, Aegeus, who, victorious, declares his intention of marrying Agilea, instead of the sorceress Medea. Agilea, however, is in love with Theseus, as is Medea, who is ready to accept the royal suggestion that she marry him. Theseus, in triumph, is acclaimed as king and declares his love of Agilea, causing Medea to seek revenge by provoking the jealousy of Aegeus. Catastrophe is averted when Aegeus recognises Theseus as his son, and Medea’s final attempts at destruction, through her spectacular magic powers, are frustrated by the goddess Minerva.
Handel’s third opera for London has a fine and largely original score, relying less on borrowing from earlier works than was often the case. Dramatically it suffered because of its libretto, designed for the conventions of the French theatre, and because of cuts made in the text and in recitative that made the complexities of the action more difficult to follow. It received 13 performances, a successful outcome that would have been more profitable had not the Irish impresario Owen Swiney, manager of the Queen’s Theatre, found it necessary to abscond, leaving the singers unpaid.