Ilia opens the third act, bewailing her unhappy love (aria, 19). Idamante surprises her, and declares his resolve to seek death in combat with the monster who is laying waste the land; this leads to a disclosure of her love, and the two express their happiness in a duet (20). Idomeneo, entering with Electra, discovers them; he cannot bring himself to acknowledge to Idamante the true cause of his mysterious behaviour, but commands him anew to leave Crete at once, and seek an asylum in a distant land. The various emotions of those present are expressed in a quartet (21). Idamante having departed, Arbace enters and announces that the people are hurrying with the high priest at their head to demand deliverance from the monster; Idomeneo goes to meet them, and Arbace expresses his earnest wish for the happiness of his ruler (aria, 22). On an open space in front of the castle the high priest appears with the multitude; he describes the ravages of the monster, which can only be terminated by the fulfilment of Idomeneo's vow, and demands to know the name of the promised victim (23). When Idomeneo names his son as the sacrifice, horror seizes the people (chorus, 24). During a march (25) Idomeneo with his subjects enters the temple of Neptune, and while the priests prepare for the sacrifice they offer their solemn prayers to the god (26); cries of joy are heard from afar, and Arbace hastens in and announces that Idamante has slain the monster in heroic combat. Idamante is presently borne in by priests and warriors, crowned and in white robes; he now knows his father's vow, and satisfied as to his feelings towards him, he is ready to fall a joyful sacrifice to the angry god (aria, 27). As Idomeneo is in the act of striking the fatal blow, Ilia hastens in and restrains him; she insists upon taking the place of her lover, and a tender strife arises between them, which Idomeneo listens to with emotion, Electra with rage and jealousy. As Ilia kneels before the altar, "a great subterranean disturbance is heard, the statue of Neptune totters, the high priest stands entranced before the altar, all are amazed and motionless from fear, while a deep and majestic voice declares the will of the gods": Idomeneo is to renounce the throne, which Idamante is to ascend, and to be united to Ilia (28). At this unexpected issue, Electra breaks into violent anger, and "goes off raging"; Idomeneo arranges everything according to the divine will (30), and expresses his grateful joy (aria, 31); Idamante is crowned in a pantomimic ballet, during which the chorus sing a joyful conclusion to the opera (32).[2] {IDOMENEO.} (130)