What's happening?

Stargate SG-1: 4x5

Divide and Conquer

When a member of the SGC tries to kill a Tok’ra, it is revealed that O’Neill and Carter may be victims of an untraceable form of Goa’uld mind control.

Stargate SG-1: Season 4 Episode 5
Stargate SG-1: Season 4 Episode 5
Jul. 28, 2000