The Tok'ra are forced to evacuate their newly established base under attack from the Goa'uld. They flee to the SGC's Alpha site. Tensions rise between the allied factions, the Free Jaffa, Tau'ri, and Tok'ra. Jacob and Selmak feel the end of the Tok'ra is near and Sam finds a Naquadah generator has been sabotaged to function as a bomb. Jack suspects the recently arrived Tok'ra and attempts to weed out the traitor.

SG-1 makes first contact with the planet Pangar. It seems to be a peaceful world that have recently discovered ancient Goa'uld ruins. They offer Earth their greatest discovery, a drug called Tretonin, which they say keeps them entirely disease free. In return, they want the gate addresses for specific worlds, most of which turn out to be Goa'uld home worlds. An investigation further reveals that the wonder drug is based on Goa'uld symbiotes and the Pangarans reveal another secret - they have a symbiote queen, found in the ancient ruins. When a Pangaran guard is seriously injured, SG-1 asks the Tok'ra for help. They soon realize that the queen is the founder of their race.