Stargate Atlantis takes place in the present like Stargate SG-1. A team of explorers, headed by Doctor Elizabeth Weir, leave Earth though the Stargate to search for the lost city of Atlantis, which is located on another planet in the Pegasus Galaxy. When arriving in Atlantis, the city is completely submerged, like in legend, the even occurred on another planet. While in the Pegasus Galaxy, the expedition awakens an entire Wraith population, this race feeds on Humans living in the galaxy. The expedition also discovers a new form of Replicators.