Idun is keeper of the apples that keep the gods eternally young. The Prose Edda tells the one story in which that arrangement nearly ends. Loki, forced by the giant Thjazi to lure Idun outside Asgard's walls, tricks her into stepping beyond its protection with her apples by claiming to have found finer fruit in a nearby wood worth comparing to her own. Thjazi, transformed into a giant eagle, swoops down, seizes her, and carries her back to his home in Jotunheim, apples and all. Deprived of Idun's fruit, the gods begin to age immediately and visibly, growing grey and stooped within what the text treats as a short span, a crisis severe enough that the assembled gods threaten Loki with death unless he undoes what his trick caused. Loki borrows Freyja's falcon shape, flies to Jotunheim, turns Idun into a nut to carry her more easily, and races Thjazi, now in eagle form again, back to Asgard, where the gods kill the pursuing giant at the wall the instant he crosses it. The episode is the clearest statement anywhere in the corpus of exactly how dependent the gods are on Idun specifically, rather than on youth as an abstract quality they simply possess.