The Atlantis team encounters the Hoffans, a human civilization in the process of rebuilding their society since the last attack of the Wraith. The resilient Hoffans have developed the beginnings of a drug that could potentially make them immune to their enemies. Fearing that the next Wraith culling will come before they are able to complete their tests, the leaders demand that their people be inoculated before the drug can be proven safe. Dr. Beckett argues that there is no way to know what the true effects of the drug will be. Can Beckett make the Hoffans see reason, or has their haste made them blind to the epidemic they may be unleashing upon themselves?

During an exploration of a planet with no apparent inhabitants, Dr. McKay discovers that the planet's fog-like atmosphere is actually pure energy… enough to open a wormhole back to earth.
Wanting to be sure they could return to Atlantis to continue their mission, Dr. Weir relays a message back to Stargate Command. They are told that the battleship Prometheus has been outfitted with a hyperdrive and they would be able to return to Atlantis within a month!
Back on Earth, the team is overjoyed to be with the things and people they love. However, when the Prometheus' hyperdrive is accidentally destroyed, their hopes of ever returning to Atlantis are suddenly dashed.