SG-1 teams with a Russian unit when one of their Stargate teams goes missing in a mysterious alien ziggurat.

Disaster strikes the Stargate, trapping Teal'c in transit. SG-1 must turn to Russia -- and to their enemies -- for help.

Tragedy reunites Teal'c with his son, who blames him for the death of his mother. O'Neill and Carter launch a risky plan with untested technology when Earth comes under attack by the Goa'uld.

Carter must find a way to save Earth from total destruction at the hands of the Goa'uld, who have turned the Stargate into a doomsday bomb. Rya'c joins his father on a mission to destroy the Goa'uld weapon.

General Hammond and the Pentagon reveal the existence of the Stargate to other world governments, and must defend the fact that the program is operated by the United States military.

The newly-elected president is debriefed about the Stargate program, and Vice President Kinsey makes a new play for control of the program.

Relations between the U.S. and Russia are strained when Russian military leaders claim that the U.S. government has been compromised by the Goa'uld.

As the Ori plague spreads rapidly, SG-1 hopes that the Prior who caused the disease may hold the key to its cure. Gerak tries to rally the Jaffa to the Ori's cause, prompting Teal'c and Bra'tac to initiate a resistance.

Vala Mal Doran makes contact with Stargate Command from the Ori home galaxy, and tells the story of her life undercover in a village of followers building the Ori's invasion fleet.

SG-1 discovers the village of Camelot on an alien world, and must face Merlin's security system when they go in search of an Ancient weapon. Elsewhere, Earth and its allies assemble a fleet when a working Ori Supergate is discovered.

As the Ori invade the Jaffa planet Chulak, Vala and Daniel must deal with their leader: Vala's young daughter, rapidly aged by the Ori to serve their purposes.