The Replicators begin a systematic attack of the Goa'uld, forcing Baal to come to Earth for help. The Jaffa Resistance risk their entire movement in an attempt to retake a holy city in Baal's domain.

The fate of the galaxy hangs in the balance as Sam and Jacob search for the only weapon capable of stopping the Replicator onslaught. O'Neill leads a defense of the S.G.C., while Daniel squares off against Replicator Carter.

While Daniel finds himself in a mysterious diner suspended between death and ascension, Jacob's fate takes an unexpected turn, Jack and Sam consider their romantic lives, and Anubis unleashes his plan for galactic destruction.

Martin Lloyd seeks out SG-1 for assistance when his failed TV show based on the real Stargate program becomes a feature film.