The Ori's plague is spreading inexorably across Earth, threatening to become a global pandemic. Carter and Orlin search desperately for a cure, but Orlin has grown weak: His Ancient knowledge is too overwhelming for his human brain to handle. Meanwhile, on Dakara, Gerak's commitment to the Ori has led him to become a Prior. Flaunting his newfound mystical powers, the arrogant leader seems poised to convert the entire Jaffa nation to Origin. Teal'c and Bra'tac, however, can't bear to watch the Jaffa fall into servitude to these new false gods. Accordingly, they persuade their followers to assemble a fleet and rebel openly against Gerak's vastly superior forces. It's a terrible gamble, but Teal'c hopes that, faced with civil war, Gerak will ultimately betray the Ori rather than kill thousands of his Jaffa brothers and sisters. With billions of human and Jaffa lives thus endangered, Daniel and Mitchell are relieved to find a ray of hope on their mission to capture a Prior alive: The reclusive and powerful Sodan warriors - who recently converted to Origin - have already renounced their new religion. Having witnessed the Priors' murderous tactics for themselves, they now vow to help Daniel and Mitchell trap one of the deadly missionaries with Carter's untested weapon. The weapon actually works (eventually), leaving Mitchell and Daniel face-to-face with a very powerless, very angry Prior. They draw the blood sample that Orlin needs and send it back to Stargate Command. Next, they try to talk the Prior into switching sides, knowing that his help would be invaluable in curing the plague. Unsurprisingly, however, he is less than receptive to their arguments. But they're about to get assistance. On Earth, Orlin has grown too weak to help Carter and the medical team to incorporate the Prior's DNA into their antidote. Instead, he journeys to the Sodan world, where, calling upon the last of his Ancient wisdom -- and the last of his strength -- he confronts the Prior himself. Orlin's profound knowledge unnerves the Prior, who blurts out that the Ori plan to kill all the Ancients even if they must ravage the Milky Way to do it.