While searching for the Lost City of the Ancients on a distant planet, SG-1 is stunned to find Daniel Jackson alive and in human form but stripped of his memory. O'Neill convinces Daniel to return with them to the SGC, where he is reinstated for a daring mission to destroy Anubis' powerful new super-weapon!
O'Neill goes to great lengths to keep the Ancients' knowledge from falling into Goa'uld hands when the team discovers a second repository. The President replaces General Hammond with a civilian diplomat. Anubis begins a systematic assault on Earth, and the planet's only hope of salvation depends on whether SG-1 can find the Ancients' mythical Lost City.
The Sci-Fi Channel debuted the behind-the-scenes special "From Stargate to Atlantis: A Sci-Fi Lowdown" on July 5, 2004. With great anticipation for the July 9 premiere of of Stargate SG-1's eighth season and the July 16 world premiere of Stargate Atlantis, GateWorld presents these Atlantis preview shots from the special! The images include the first good look at the "puddle jumper" ship, an outer space Stargate in orbit of a planet, a Pegasus galaxy D.H.D., the male Wraith, and more.
Carter and Teal'c go in search of the Asgard to try and save Colonel O'Neill, but discover that the Asgard's enemy has returned with a vengeance. The System Lords seek an alliance with Earth against a common enemy. While the Goa'uld threaten to attack Earth, SG-1 and the Asgard make a last, desperate stand against the Replicators, which have captured Major Carter and invaded the last outpost of the Asgard civilization.
Earth is infected with a deadly Ori plague, prompting an ally from SG-1's past to come to their aid. Gerak proposes that the Free Jaffa follow the Ori religion.
This special deals with how the SG-1 series intertwined many of Earth's mythologies into its plots and story lines, and about the many alien character connections with Earth’s great mythological figures.
As SG-1 searches for an Ancient artifact which they hope can defeat the armies of the Ori, they learn more Ori ships are about to be sent through the Supergate to launch a final assault on Earth. Daniel discovers that the artifact, the Ark of Truth, may be in the Ori home galaxy, and SG-1 embarks aboard the Odyssey to find it, and pre-empt the attack. The IOA has a plan of their own and SG-1 ends up in a distant galaxy fighting two powerful enemies.
While SG-1 attends the execution of Ba'al, the last of the Goa'uld System Lords, Teal'c and Vala inexplicably disappear into thin air. Carter, Daniel and Mitchell race back to a world where history has been changed: the Stargate program has been erased from the timeline. As they try to convince the authorities what's happened, a fleet of Goa'uld motherships arrives in orbit, led by Ba'al, his queen, Qetesh (Vala), and his first prime, Teal'c. SG-1 must find the Stargate and set things right before the world is enslaved by the Goa'uld.