is the 16th episode of the eighth season of Stargate SG-1 and the first half of a pivotal two-part event. Originally aired in February 2005, this episode begins the process of concluding several of the series' longest-running plot arcs, specifically the Jaffa Rebellion and the Replicator threat . Plot Summary

The episode depicts a galaxy-wide crisis as the Replicators, led by "RepliCarter" (a Replicator double of Samantha Carter), launch a full-scale invasion of the Milky Way.