O'Neill and the SG-1 team return to Cimmeria after learning that the Goa'uld have invaded the planet. The team feels responsible since, on their previous visit they destroyed "Thor's Hammer," the planet's main instrument of defense against the Goa'uld. The team makes some remarkable discoveries on the planet. Samantha Carter discovers that she has the power to use the Goa'uld ribbon device. It soon becomes clear that the SG-1 team need help to fight the massive enemy force led by the System Lord Heru-ur (The 'Son' of Ra and Hathor) (Heru-ur has begun construction of three Pyramid platforms, which would enable three Motherships to land on the planet) . Teal'c, O'Neill and Olaf head out to scout the Goa'uld encampment and soon find themselves face to face with the enemy. Meanwhile, Daniel Jackson, Samantha and Gairwyn search for the Hall of Thor's Might, where they believe they might find weapons to defeat the Goa'uld. They find the hall, where they are presented with a series of tests by a hologram of Thor, the Asgard god who guards the planet. Can they pass the tests and find a way to defend the planet? And, can they do it before Heru-ur's army wipes out the rest of the Cimmerians and the rest of the SG-1 team?