The Stargate base is put in deadly peril when it is contaminated with a dangerous infection which causes its victims to become mindlessly animalistic brutes.

O'Neill, Carter and Teal'c return through the Stargate shell-shocked and distressed to announce that Daniel Jackson was killed. But Jackson was captured by the last survivor of an aquatic race, who planted false memories in the other members of SG1. Can the team remember and return to rescue Daniel?

On their first visit to a new planet, SG-1 finds it subject to totally destructive volcanic activity and saves ten natives, the Tollan, a far more technologically advanced society. Their leader Omoc isn't grateful, nor interested in such a primitive race as the earthlings or any of the 'even more primitive' planets which are prepared to host them. Only one Tollan, Narim, shows an active interest in life on earth, especially in captain Samantha Carter and the cat Schrodinger she gives him, explaining his planet was destroyed after the Tollan supplied an unlimited energy source to a primitive neighboring planet which abused it for a cataclysmic weapon. Meanwhile, the White House authorized NID colonel Maybourne to take charge over the Tollan for military purposes, exactly Omoc's nightmare.