Crichton and Aeryn race to construct a powerful weapon to fight an approaching Scarran Dreadnaught, poised to claim powerful wormhole technology that could help them conquer the galaxy. Crais and Stark deal with a Scarran who boards Talyn and tries to take command.

When Cassandra exhibits strange uncontrollable electro magnetic effects, which cause most electrical sources nearby to burn out, she is taken back to the SGC. In investigating the cause, they are lead to believe Nirrti is involved in the strange development of children on Cassandra's planet. The team struggles to find the answer, or the cure, to Cassandra's situation. However, they get a nasty shock related to their investigation of Nirrti's seemingly abandoned lab on Cassandra's planet.