Carter is possessed by a Goa'uld who claims to be an enemy of the System Lords – Jolinar of Malkshur, who is being hunted by an assassin that has followed her to Earth.
Jackson discovers that his wife has returned to Abydos, and is about to give birth to Apophis's son. O'Neill is approached by a reporter who threatens to expose the Stargate program to the world.
Teal'c is infected with deadly venom from a giant insect, and begins a terrible transformation. When he escapes the S.G.C., SG-1 must find him before Colonel Maybourne does.
SG-1 locates the Tok'ra, a Goa'uld resistance movement who oppose the System Lords, and attempt to form an alliance. Jacob Carter's cancer brings him near death.
While SG-1 tries to form an alliance with the Tok'ra, a spy betrays the rebels to the Goa'uld. Jacob Carter finds that the Tok'ra may be his only hope of survival.
SG-1 is accused of stealing an important weather-controlling device, sending a primitive planet into chaos. The team discovers that Earth's second Stargate is being misused.
After gating to a world on the edge of a black hole, the S.G.C. cannot disengage the Stargate – threatening all of Earth with a time-distorting gravity field.
SG-1 discovers an elderly man known for developing technology to fight the Goa'uld, who tricks Daniel into switching bodies with him – the reward the man believes he is owed for his work.
Apophis, SG-1's greatest enemy, seeks sanctuary from a rival Goa'uld and ends up near death in the S.G.C. infirmary – completely at the mercies of his human foe.
A young boy arrives through the Stargate, and warns of plot by invisible aliens to kill all of the human race in order to rob the Goa'uld of potential hosts.
O'Neill, Carter and Jackson awaken from stasis in what appears to be the S.G.C. – almost 80 years in the future – and are asked to recall key events from their journeys.
