.O'Neill, being happy that they have saved the planet again, plans a relaxing fishing trip to Minnesota. However, SG-1 is once again called into action, as at least one Replicator has survived Thor's spaceship's crash into Earth's ocean. A Russian sub has reported being attacked by metal bugs just before contact with the sub is lost. Thor makes a reappearance to thank the team, but he also tells them the Asgard are continued to be greatly threaten by the Replicators at the moment. Carter agrees to go with Thor to help the Asgard try to defeat the Replicators attack, hoping to use, as the Asgard call it, her earthling primitive ideas. At the same time, O'Neill and Teal'c rush to the Russian sub, now under US control, to see if they can stop the Replicators from gaining a foothold on Earth. If either team fails, the Earth will be doomed to be overrun by the Replicators.