Act I
Island of Crete. Ilia, daughter of King Priam, loves Prince Idamante, son of Idomeneo, but she hesitates to acknowledge her love. Idamante frees the Trojan prisoners. He tells Ilia, who is rejecting his love, that it is not his fault that their fathers were enemies. Trojans and Cretans together welcome the return of peace, but Elettra, jealous of Ilia, does not approve of Idamante's clemency toward the enemy prisoners. Arbace, the king's confidant, brings news that Idomeneo has been lost at sea while returning to Crete. Elettra, fearing that Ilia, a Trojan, soon will be Queen of Crete, feels the furies of Hades tormenting her.
On a deserted seashore, after the shipwreck, Idomeneo recalls the vow he made to Neptune -- to sacrifice, if he arrived safe, the first living creature he meets on shore. Idamante approaches him, but because the two have not seen each other for a long time, recognition is difficult. When Idomeneo realizes the youth is his own child, he orders Idamante never to seek him out again. Grief-stricken by his father's rejection, Idamante runs off. Cretan troops disembarking from Idomeneo's ship are met by their wives, and all praise Neptune.
Act II
At the king's palace, Idomeneo seeks counsel from Arbace, who says another victim could be sacrificed if Idamante were sent into exile. Idomeneo orders his son to escort Elettra to her home, Argos. Idomeneo's kind words to Ilia move her to declare that since she has lost everything, he will be her father and Crete her country. As she leaves, Idomeneo realizes that sending Idamante into exile has cost Ilia her happiness as well as his own. Elettra welcomes the idea of going to Argos with Idamante.
At the port of Sidon, Idomeneo bids his son farewell and urges him to learn the art of ruling while he is away. Before the ship can sail, however, a storm breaks out, and a sea serpent appears. Recognizing it as a messenger from Neptune, the king offers himself as atonement for having violated his vow to the god.
Act III
In the royal garden, Ilia asks the breezes to carry her love to Idamante, who appears, explaining that he must go to fight the serpent. When he says he may as well die as suffer the torments of his rejected love, Ilia confesses her love. They are surprised by Elettra and Idomeneo. When Idamante asks his father why he sends him away, Idomeneo can only reply that the youth must leave. Ilia asks for consolation from Elettra, who is preoccupied with revenge. Arbace comes with news that the people, led by the High Priest of Neptune, are clamoring for Idomeneo. The High Priest tells the king of the destruction caused by Neptune's monster, urging Idomeneo to reveal the name of the person whose sacrifice is demanded by the god. When the king confesses that his own son is the victim, the populace is horrified.
Outside the temple, the king and High Priest join with Neptune's priests in prayer that the god may be appeased. Arbace brings news that Idamante has killed the monster. As Idomeneo fears new reprisals from Neptune, Idamante enters in sacrificial robes, saying he understands his father's torment and is ready to die. After an agonizing farewell, Idomeneo is about to sacrifice his son when Ilia intervenes, offering her own life instead. The Voice of Neptune is heard. Idomeneo must yield the throne to Ilia and Idamante. Everyone is relieved except Elettra, who longs for her own death. Idomeneo presents Idamante and his bride as the new rulers. The people call upon the god of love and marriage to bless the royal pair and bring peace.
Meanwhile, back at the ranch ......