Odin, the imprisoned ruler of the Norse gods, is held captive by Loki and the King of Hell within the Land of the Dead. His confinement ignites the central conflict when a Valkyrie rescue effort fails, resulting in their enslavement by demons. To force his release, Odin enacts a catastrophic contingency: he seals the river source nourishing Yggdrasil, the World Tree, ensuring its eventual withering and the annihilation of all realms. This act serves as both bargaining leverage and a doomsday device, pressuring his captors to free him or face mutual destruction.

Before his capture, Odin designated Valkyries Svidia and Sigurd as guardians of physical keys required to unseal the river. Concealed within their bodies, these keys demand voluntary surrender to activate. His strategic foresight in placing the keys establishes the primary objective for others, though he remains physically confined. Odin's imprisonment and choices indirectly drive the exploitation of the Valkyries, as Loki targets Svidia and Sigurd to extract the keys and avert global collapse.