Idun was the goddess of spring and youth in Norse mythology. She was the guardian of the apples of youth that grew in Asgard and supplied them to the gods to maintain their youth. In one story, Loki, in order to save his own skin, agrees to help the giantess Thjasse kidnap Idun to procure her apples. While Idun is being held prisoner, the Aesir, without access to the apples, start to age. They demand that Loki return Idun to Asgard, which he manages to do.