The plague continues to spread among the US population and the President has quarantined the nation. Teal'c is pleading with the Jaffa High Council to reject Origin, but Gerak arrives, having been transformed by the Ori into a Prior. Cameron and Daniel seek the blood of the Prior that caused the plague in order to cure it, but have once again been captured by the Sodan.

SG-1 is tasked to accompany members of the International Oversight Advisory, including Richard Woolsey, on a tour of the Gamma site. The visitors are suitably impressed but everyone is put in danger when a carnivorous insect escapes from the lab. The base is locked down and no one is allowed to travel through the gate. The bug is linked to the Ori - it's appeared on several planets that they've visited - and Daniel thinks it may be their follow-up to the virus. SG-1 and the IOA visitors take refuge in a cave, but Gen. Landrey is left with little choice but to flood the planet with a deadly neurotoxin to destroy the bugs. SG-1 looks for away out before that happens.