 On a planet with an extremely toxic atmosphere, there exists a bubble within which exists a livable atmosphere. Inside the bubble lies a seemingly less advanced society of humans. They reveal to SG-1 that they once were highly industrialized and poisoned the air. They voluntarily simplified their lives and constructed the barrier to keep out the bad air. They also show SG-1 their "link", a neural interface that gives them access to all their computer records, including history, science, etc. When one of the citizens disappears in the night and the entire population forgets she existed, SG-1 begins to think things are not what they appear to be.