 The Russian SG team brings back a man who claims that his people are being experimented on by Nirrti. SG-1 investigate where the experiments are conducted, with the Russian SG team as backup. The inhabitants worship Nirrti as their god and savior from a terrible plague. SG-1 attempts to use the same device Nirrti used on the people to reverse the mutations, but the people turn on them at the arrival of Nirrti.