A new Stargate team embarks on a dangerous mission to a distant galaxy, where they discover a mythical lost city -- and a deadly new enemy.

Sheppard tries to convince Weir to mount a rescue mission to free Colonel Sumner, Teyla, and the others captured by the Wraith.

Elizabeth Weir wakes up in a mental institution, where she is told that the expedition to Atlantis and the Stargate are figments of her imagination.

The Atlantis expedition is stunned to learn that a ship full of Ancients is returning to reclaim their lost city.

The Atlantis team goes against orders to try and save Atlantis from Replicator control -- and to rescue General O'Neill and Richard Woolsey, who are trapped in the occupied city.