SPOILER ALERT: you may prefer to follow the story as the performance unfolds.
Returning from the Trojan War, the Cretan fleet has been caught in a storm. The prisoners, which include the princess Ilia, have been rescued at sea.
Ilia is torn between loyalty to her annihilated people and her sudden feelings for Idamante, the Cretan prince who just saved her life. When she rejects his declaration of love, Idamante insists that it is not his fault their fathers were enemies and sets the Trojan prisoners free.
Cretans and Trojans celebrate peace and liberty but Elettra admonishes Idamante for liberating the hard-fought enemy. Idamante insists that victory is enough and that the conquered can live happily but is interrupted by Arbace’s news of his father’s death. Idamante runs to the coast, leaving Elettra infuriated that Idomeneo’s son now has the freedom to rule as he pleases and to choose his queen.
News of Idomeneo’s demise is premature. Out at sea, the king and his men flounder in the furious waves. The storm subsides and the shipwrecked sailors survive. Alone, Idomeneo regrets the pact he just made with Neptune, the god of the sea: in exchange for his own life, he must sacrifice the first person he meets on land. Ten years since Idomeneo sailed for Troy, he does not know the man who approaches. When he recognises his own son, he orders Idamante to stay away from him.
The people of Crete praise Neptune for Idomeneo’s safe return.
Idomeneo asks Arbace to help avoid sacrificing Idamante to Neptune. They devise a plan to send Idamante away and Arbace leaves to inform Idamante and Elettra that they will travel to regain her throne in Argos. Ilia tells Idomeneo that she has found happiness in Crete. She praises Idamante’s kindness, which leads Idomeneo to deduce that she and his son are in love. He suspects Idamante’s reason for releasing the Trojans, believing it the basis for Neptune’s choice of victim. He envisages the grief that he will share with Ilia if he kills his son. Elettra thanks Idomeneo for his promised help in returning her to power and is delighted to discover that Idamante will accompany her on the journey.
Idomeneo bids farewell to Idamante and Elettra but a new storm prevents them from setting sail. When a sea creature then attacks, the people conclude that Neptune is offended. Idomeneo claims responsibility but challenges the legitimacy of the gods.
Ilia secretly regrets rejecting Idamante’s love. When the prince declares his intention to attack the sea monster and does not expect to survive to battle, Ilia cannot contain her feelings. The lovers are discovered by Idomeneo and the jealous Elettra. Idamante asks his father to explain why he spurns him but Idomeneo banishes him from Crete. Ilia begs Idamante to take her with him and for Idomeneo to change his mind; Elettra desires revenge; Idomeneo protests against Neptune; Idamante leaves alone.
Arbace informs Idomeneo that the people, led by the High Priest of Neptune, are demanding to see him. Arbace laments the impending downfall of Crete.
The High Priest reveals the devastation that the monster has wrought on Idomeneo’s people. He urges the king to make a sacrifice. Idomeneo lets it be known that Neptune’s victim must be his son. The priests prepare the ritual. The prayers are interrupted by sounds of rejoicing and Arbace reports that Idamante has defeated the monster. However, Idomeneo realises that Neptune will only be satisfied by the death of his son. Idamante is brought before the altar. He is prepared to die for his country and forgives his father for what must be done. The people are his children too. Just as Idomeneo raises his axe, Ilia bursts in and offers to die in Idamante’s place. Her loving willingness to die for a former enemy provokes a response from the heaven. It is declared that Idomeneo must abdicate and leave Idamante and Ilia to reign in peace.
John La Bouchardière, May 2012