Stargate SG1 - Season 6, Episode 12: Unnatural Selection (2)
Trailer
Season 6 opens with Master Bra'tac arriving with bad news: Teal'c's wife is deathly ill, and Teal'c leaves to be with her. Shortly thereafter, the gate is opened but nothing comes through. Then Carter discovers a very low power signal that is slowly building an overload powerful enough to destroy the Earth.