A dramatic
opera by
Mozart, first performed in Munich in 1781. Its full name is
Idomeneo, Re di Creta, and tells of
Idomeneus, King of
Crete, who is delayed by a storm on the way back from the
Trojan War. Vowing to sacrifice to
Neptune the first being that he meets on shore if he is allowed to land safely, he lands safely and is met by his own son
Idamante.
For an opera, it has a happy ending. Instead of a huge pile of bodies on the stage by the end, it has that classical Greek drama idea of reconciliation and substitution, that occurs in some of their stories, so that both Idamante and Idomeneo are spared. There is a love story too. Ilia is a daughter of the defeated King Priam of Troy, and a captive of Idomeneo, and she and Idamante are now in love. There is a love rivalry too: Elettra is also in love with Prince Idamante.
In Act 1 King Idomeneo is about to arrive home so in anticipation his son Idamante proclaims a general amnesty for his prisoners, but a storm endangers the king, and he makes his tragic vow. Idamante begins searching for him on the shore. (The Trojan War lasted a very long time and they don't recognise each other at first.) The same sort of tragic vow was made by the Biblical leader Jephtha, subject of an opera by Handel.
In Act 2 Idomeneo tries to avoid the vow by getting rid of Idamante. He sends him to escort Elettra away to Argos. This pisses off (a) Neptune, who wants his sacrifice; and (b) Ilia, who is jealous. Neptune sends a monster to ravage the coasts of Crete, and Ilia probably makes everyone's life a misery too. The people of Crete gnash their teeth and wonder what unplacated sin by what miserable sinner is putting them under this curse. (Okay, the monster does kill lots of background Cretans, but no main characters.)
In Act 3 it gets complicated (well it's an opera, it has to). Idamante goes off to kill the monster -- I don't know how far he got towards Argos --, and he succeeds, and now Elettra is jealous of Ilia. In fact at the end of it she goes mad with jealousy and has a good old-fashioned mad scene out of it. Having killed the monster, Idamante is a hero, and the High Priest can't quite work out whether the threat is over or whether they still need to kill him to placate Neptune. Then Ilia offers herself, a poor enemy bondswoman, as a sacrifice in her lover's place. Neptune's voice comes out of the sea saying that this nobility is good enough for him, and for once nobody is going to have to die. Idomeneo proclaims Idamante and Ilia his ordained successors, and abdicates.
The libretto was by Giambattista Varesco, a priest in the court chapel at Salzburg; based on Danchet's libretto for Andre Campra's 1712 opera Idoménée, and of course largely on the classical legend. Mozart was commissioned by Elector Karl Theodor of Bavaria. The first Idomeneo was Anton Raaff.
Listening to a performance by the Berlin Philharmonic under Sir Simon Rattle, broadcast on Radio 3, as I write
Concise Oxford Dictionary of Opera
www.mozartproject.org/compositions/k_366__.html