The System Lords approach Earth for an alliance to stop Baal from conquering the galaxy. Teal'c and Carter travel to the Halla system to find the Asgard who are O'Neill's only hope.

O'Neill uses the memory of the Ancients to help the Asgard save their civilization once again.

A Russian officer arrives at the SGC with an apparent infectious virus. However, the SGC is put into lock down after they discover that the Russian Officer does not really have a virus after all, but is inhabited by the remains of the SGC's old nemesis , Anubis.

The President sends an assistant to look into the running of the SGC, before the President comes and formally blesses O'Neill as commander of the SGC. However, problems keep cropping up during the assistant's visit.

Daniel is trapped on an alien planet in a state of cold war, each side with enough weapons to destroy the other. Will Daniel be able to contact Earth and stop a radical group controlling the country and return to Earth?

SGC scientists have come up with a virtual reality simulation training exercise. Teal'c is in the machine attempting to stop a Kull warrior taking over the SGC, but he gets stuck when the program keeps adding more obstacles.A SG-1 is told that disconnecting Teala 'c from the simulator prematurely might kill him.

Teal'c moves into an apartment off base, and then becomes the chief suspect in a murder. Teal'c is proven innocent after Dr. Jackson goes missing, and it is revealed the Trust are still active, and are taking aggressive measures to get what they want.

When a corporate billionaire threatens to expose the Stargate program, SG-1 is tasked to silence him. What they find in the process leads to a new life for the billionaire, which he didn't anticipate, or believe could happen.

Teal'c finds out his son is to be married, which then causes some tension between the two. Teal'c is later ambushed off world, at meeting with the warriors of Hak'tyl, as they are planning a rebellion against the Goa'uld Moloc.

The Stargate disappears right in front of the SGC crew, leaving the SG-1 team to figure out who took it. At the same time, someone is attacking and killing the Jaffa with a deadly gas on various worlds, and the Jaffa blame the Tok'ra for these deaths. Are these two events connected? SG-1 must find out the answer to this, and the answer ends up being closer to home than they would expect.

Stargate Command receives two disturbing bits of news; a replicator generated Carter exists, and that Fifth and the Replicators are headed to Earth. The replicated Carter tells Stargate Command she wishes to be destroyed by the disruptor weapon created by O'Neill. However, can the replicator Carter be trusted? Or is this some sort of trap set by Fifth. Either way, the team has no choice but to find out.

General Hammond, who is set to designate a crew for the Prometheus on a mission to determine if the Atlantis team is okay, designates himself to command the trip. He picks Jackson to join the team over O'Neill's objection. After embarking on the trip, the Prometheus happens upon an Al'kesh ship with a Super Soldier on board. The Super Soldier is able to transfer the Prometheus' crew to the Al'kesh and take over the Prometheus. Unfortunately, the Al'kesh's life support is nearly depleted. Daniel Jackson finds himself the only one left on the Prometheus. He must try to defeat the Super Soldier, who turns out to be a female, Vala, who is a smuggler just posing as a Super Soldier. Jackson must discover her intentions, and foil them, and plus rescue the Prometheus' crew, all at the same time.

The SGC learns that some of the Goa'uld fleeing from Ba'al's fleet may be headed to the planet the Tok'ra relocated Col. Maybourne to. Against his better judgment, O'Neill sends SG-1 to retrieve Maybourne before he is captured. However, SG-1 finds that Maybourne has become the planet's leader, and is even somehow able to foresee the future. He has even foreseen that SG-1 will defeat the Goa'uld's attempt to reclaim the planet. Even as the team struggles with what to do about Maybourne and the rest of his followers not wanting to leave before the Goa'uld arrive, they makes a staggering discovery.

The Russians think the US government has been infiltrated by the Goa'uld.The Trust are trying to provoke Russia and the US into a nuclear war destroying themselves. Will SG-1 be able to find out what is going on before it's too late?

After breaking into Jack's house and holding Jack at gunpoint, a barber describes how he has been seeing SG-1's missions over the last 8 years, through the accidental use of an ancient communication device.A

As the Replicators threaten to take over the entire galaxy, Carter and Thor work on a new weapon, while an alliance is made with the Goa'uld System Lord Ba'al.

The Replicators overrun the Stargate Command, and Teal'c and the Jaffa must fight against Baal. Daniel gets his mind probed by the RepliCarter, and Carter and her father Jacob search frantically for the Ancient Weapon on Dakara.

Finding himself located in a mysterious diner, Daniel learns he is trapped between being ascended and dying. Meanwhile, Anubis is planning galactic destruction, as Sam and Jack consider their personal lives.

The future is altered by SG-1 when they travel back to Ancient Egypt to recover a ZPM.

A plan is formulated to correct the timeline by Carter, O' Neill, Teal'c and an alternate Daniel Jackson.