En route to the infirmary after an extended mission, SG-1 learns that part of the SGC has been sealed off due to a chemical leak. Soon after, during their routine examinations, Dr. Fraiser injects each member of the team with a sedative, rendering them unconscious. Teal'c is the first to awaken, and secretly observes Dr. Fraiser and General Hammond talking with two aliens. The General orders Teal'c and Carter placed in holding cells. Feigning unconsciousness, he waits until he and his escorts are away from the infirmary before overpowering the guards and waking Major Carter. Carter and Teal'c quickly realize that they cannot trust anyone in the SGC and must seek help outside the base. During the escape, one of them is captured. The other must rely on the one person they can't trust in order to save the SGC and the Earth from invasion.