After a particularly rough ride through the Stargate, SG-1 arrives on a planet with a Norweigan-like society. As they meet the villagers, the sky and the sun suddenly change to an orange-red color, rendering the whole planet in an orange glow.
The villagers immediately think it's Ragnarok, the End of Dawn, while Samantha discovers that the wormhole they came through must have gone directly through the sun. Some heavy elements must have triggered a reaction inside the sun, so that its light pattern changed, and the planet's plant life will be destroyed.
While the locals start praying to Freyr, an Asgard posing as a god, SG-1 tries contacting the Asgard in a more effective way. When the Asgard decline to intervene, the team needs to try and reverse the reaction in the sun on their own