Earth's secret offworld base is attacked by Anubis' forces, and Major Carter finds herself being hunted by the enemy. General Hammond and Jacob Carter make an unnerving discovery about the Earth-Tok'ra alliance.
O'Neill goes to great lengths to keep the Ancients' knowledge from falling into Goa'uld hands when the team discovers a second repository. The President replaces General Hammond with a civilian diplomat.
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.